For months he had dreamed of crossing the finish line. At mile 24 of the Boston Marathon, the fatigue had hit, and Dennis J. Purcell '13 did not think twice when he heard someone say “explosion.” He continued to run. Ten minutes later, when his mother and sister pulled him to the sidelines and alerted him of what was unfolding around mile 26, he realized he would not make it to the end of the course.

Two fatal bombings had interrupted Boston's annual celebration of athleticism and patriotic spirit. What started Monday would span the week, culminating in a manhunt for the suspects that would paralyze greater Boston and place members of the Harvard community within miles of a suspected terrorist. In the face of an ever-evolving crisis, the moving parts of Harvard's complex network of security, communication, and campus services mobilized to react to the unfolding events.

Monday, April 15, approx. 2:50 p.m.

When reports of a potential terrorist attack in Boston reached Harvard, University President Drew G. Faust and Executive Vice President Katherine N. Lapp were both in Holyoke.

Lapp was waiting to start a meeting with a University Health Services administrator when she answered a call that alerted her of the tragedy. Faust, walking out of a doctor's appointment herself, bumped into someone who had heard reports of the bombing on the radio.

Both immediately rushed to Massachusetts Hall, the home of Harvard's central administration. There administrators mobilized, scrambling to gather information about Harvard staff, faculty, and students who were at the Marathon. Reaching out to resident deans as well as students, officials began the process of checking in on the more than 100 Harvard affiliates potentially caught in the crisis. That, Lapp later reflected, was “our main focus.”

Harvard University Police Chief Francis D. “Bud” Riley was on vacation with his family in Washington, D.C., when he saw news reports of the explosions in Boston. It soon surfaced that the explosions had been set off by man-made pressure-cooker bombs, prompting Riley to swiftly book an early morning flight home for the next day. On Monday, he stayed in constant communication with the HUPD deputy chief left in charge of operations, who would man the control center in Cambridge in Riley's absence.

Monday, 3:40 p.m.

Unbeknownst to the broader Harvard community, by 50 minutes after the first explosion the University had tapped into its emergency management structure and assembled both its Incident Support Team, which includes representatives from across the departments and Schools, and the Crisis Management Team, which brings together School-level administrative deans, Massachusetts Hall officials and University vice presidents. At the same time, rumors about what had happened in Boston and whether it posed a threat to the Cambridge area circulated through House email lists and over social media. Frequent tweets from the Cambridge Police Department alerting followers of “SUSPICIOUS PACKAGE” reports fueled the state of confusion.

Monday, approx. 4:10 p.m.

Undergraduate Council president Tara Raghuveer '14 had been in an afternoon class for only a few minutes when she decided to send an email to HUPD requesting a status update and inquiring about whether students should be concerned. Though HUPD had already decided to station additional officers throughout campus for the purpose of increasing the visible police presence, undergraduates had yet to receive an official communication from the administration regarding what was playing out in Boston. “I was on my email and Facebook, and everything was spinning like crazy,” Raghuveer said, adding that she was also checking the news online. “Needless to say, I wasn't paying a lot of attention to what was going on with the course material for that day.”

Monday, 4:28 p.m.

In offices across Harvard's campus, members of the Incident Support Team and Crisis Management Team convened for a conference call, one of many that week, to assess the developing situation and share updates on the status of each School. According to Vice President for Campus Services Lisa Hogarty, a member of the CMT, during that call administrators decided it was time for Harvard to disseminate what it knew. Per their discussion, Lapp would send an email to the entire Harvard community. Around the same time, the Harvard Extension School announced that it had cancelled its classes, sections, and events due to the temporary suspension of portions of the Massachusetts Bay Transportation Authority, a system which many of its students and faculty depended on to commute to and from school. After HUPD confirmed that an explosion had occurred at the John F. Kennedy Presidential Library in Boston, it contacted Kennedy School administrators and cautioned that the school might similarly be a symbolic target. About 20 minutes after the conference call began, the Kennedy School was evacuated. The library explosion in Boston was later determined to be caused by an unrelated fire.

Monday, 5:17 p.m.

In Harvard's first University-wide communication since the explosions, Lapp sent an email stating that officials were continuing to monitor news reports and that, at the time, they had received no notification of injured Harvard affiliates. Gathering accurate details about the bombing was complicated, Lapp later said, because “the incident was not right outside our door or on our campus, where we could get more information more accurately, more quickly.”

Monday, approx. 6:10 p.m.

Students gathered around laptops and televisions in House social spaces to watch President Barack Obama address a nation stunned by the bombings. “Boston is a tough and resilient town, and so are its people,” Obama declared. “The American people will say a prayer for Boston tonight.” Not long afterwards, undergraduates received another University email, this time from Faculty of Arts and Science Dean Michael D. Smith, announcing that FAS classes and sections would be cancelled that evening. Later, undergraduates received an alert through MessageMe—an opt-in notification system through which Harvard sends news alerts via text, email, and voicemail—stating that the campus faced no threat and reiterating that evening classes had been called off. Raghuveer spent part of that evening emailing administrators about their communication with undergraduates throughout the day. In an email exchange with administrators that was forwarded to a House list, Raghuveer requested more information on what was happening at Harvard. Reflecting on the day, Lapp later identified communication as an area the University must be mindful of during future crises. “I think the primary lesson learned is to figure out, when we communicate, how quickly we can do it while balancing the need to have accurate information,” she said during an interview in May.

Thursday, April 18, 10:48 p.m.

With Monday's events removed in both time and distance, it seemed that Cambridge had returned to equilibrium. But the shooting of an MIT police officer on MIT's campus brought back the violence, frighteningly close to home. With the shooter at large, Riley rushed from his home to HUPD headquarters. The police chief and other officials assessed the developing situation and decided they needed more manpower. A HUPD officer who starts a shift at 3 p.m. normally leaves by 11 p.m., but that evening, Riley asked them to stay longer. Officers remained on duty until 7 a.m.—twice the time they would have worked on a normal day. Over the course of the night, other officers would call in and volunteer to help.

Thursday, 11:15 p.m.

Hogarty was asleep in her bed when her phone rang around 11:15 p.m. alerting her of violence close to campus. She and other administrators on the CMT were called at home to deal with what was unfolding in Cambridge. They would stay near their phones constantly throughout the night, translating news about the ongoing manhunt in the Greater Boston area for two men later identified as the the Boston Marathon bombers into decisions about Harvard. That information was translated into news alerts for the Harvard community.

Thursday, approx. 11:30 p.m.

In the virtual control room, HUPD spokesperson Steven G. Catalano was managing the University's communications system. He would later pass that responsibility along to a Harvard Public Affairs and Communications official. While on Monday undergraduates received only one MessageMe alert, on Thursday between 11:30 p.m. and 11:45 p.m. alone the University issued three communications warning students to stay out of the MIT area. Catalano later said that the proximity of the shooting to Harvard's campus and the possibility that Harvard affiliates might be near the scene of the crime contributed to the relative frequency of Thursday's alerts. The situations had to be treated “differently,” he said. At around midnight, the two brothers who killed the MIT officer and are suspected to be the marathon bombers drove a hijacked car down Soldiers Field Road, passing by Harvard Business School. But there was no point that night, Riley later said, at which he felt there was a direct threat to Harvard's campus.

Friday, April 19, 12:40 a.m.

Harvard issued a MessageMe alert that read, “MIT shooter situation remains active.” At around the same time, a shootout with police in Watertown left one of the two bombing suspects fatally injured as the other escaped. News outlets later reported that the surviving man, Dzhokhar Tsarnaev, had previously worked as a lifeguard at the Malkin Athletic Center pool. Although the search for a former Harvard employee had left Harvard's campus, Watertown borders Cambridge, so the sense of peril among students was far from gone. As on Monday, they turned to the Internet in search of answers. Purcell, shocked by reports of gunshots fired, kept close track of incoming news through Twitter and various web sources from a friend's room in Pforzheimer House. He would not fall asleep until the early hours of the morning.

The MessageMe system was silent in the hour following the 12:40 a.m. alert. Raghuveer, still concerned about the scarcity of Monday's communications, sent an email to College administrators that was carbon copied to the Undergraduate Council list asking for an official update about the situation at Harvard. Fifteen minutes later, at around 2 a.m., Harvard sent out another MessageMe alert that stated, “HUPD monitoring the situation.” Around 3 a.m., staffers in the Office of Student Life called Raghuveer asking what undergraduates wanted to learn through communications.

Friday, approx. 4:30 a.m.

Hogarty first heard mention that Harvard might shut down for the day around 4:30 a.m., as officials began to grasp the significance of the shootout in Watertown. She said that was when administrators realized the manhunt was “much more of a broad thing.” They were considering a decision that could not be made lightly. Although the University had shut down twice that year in the face of extreme weather, before then it had not shut down since Boston's infamous blizzard of 1979.

Friday, 5:52 a.m.

“The University is closed due to public safety concerns,” read a MessageMe alert timestamped 5:52 a.m. As residents of Cambridge, Harvard students had been told to shelter indoors. The Greater Boston area was on lockdown.

Friday, approx. 7:00 a.m.

“We wanted to make sure he wasn't hiding here,” Riley later said. Knowing that Tsarnaev had been a Harvard lifeguard, HUPD dispatched officers to the University's athletic facilities in Allston sometime around 7 or 8 a.m. They did not find anything suspect.

Many Harvard workers had reported on time Friday to early morning shifts, unaware of the trajectory of the previous night's dramatic events. Managing Director of Harvard University Dining Services David P. Davidson had organized a call that morning to determine the capacity of various eateries on campus. Since nonresidential buildings were closed, he redeployed employees who would normally staff eateries like Greenhouse Cafe to the Houses. Annenberg and all residential dining halls opened for breakfast as usual on Friday morning. Undergraduates gathered in dining halls to eat and monitor the ongoing situation.

Behind the scenes, CMT held conference calls every hour on the half hour. With the campus waking up, those discussions had expanded to include the administrative deans capable of voicing school-specific problems. In the hours to come, administrators advised the Class of 2017 not to come to Cambridge for Visitas, the campus preview weekend for admitted students whose programs were slated to begin that afternoon. The Law School canceled the spring reunions that had been scheduled for the following days. “Those were two very big decision points,” Hogarty said. “Safety was the absolute most important thing.” Harvard was adjusting to life under lockdown.

Friday, approx. 12:00 p.m.

Throughout the day, the University's crisis management communication system connected the University's top officials as they reacted to the day's events. With most campus eateries closed, by lunchtime administrators had arranged for Law School and Graduate School of Design students to eat at the College's Annenberg dining hall. Police officers and custodians joined graduate students as guests.

In the next few hours, although police continued the hunt for the Marathon bomber, things in Cambridge began to settle. Students began to venture into the Yard. Harvard Square businesses started to open previously shuttered doors. By mid-afternoon, members of the CMT, realizing things had begun to calm, transitioned to calls every hour and a half.

Friday, approx. 6:00 p.m.

As the afternoon wore on, Harvard had already started healing. Faust heeded official warnings to stay inside throughout the day and chimed in on CMT conversations from her Elmwood estate. When she finally ventured out of her home at 6 p.m., around the same time the lockdown was lifted, she joined Dean of the College Evelynn M. Hammonds in Annenberg. There, the administrators chatted with freshmen about their experiences during the week that for many would be the most memorable of the academic year. On the other side of campus, University Provost Alan M. Garber '76 dropped by the Quad dining halls to do the same. A few hours later, Harvard affiliates watched from their computers and televisions as authorities apprehended Tsarnaev in a Watertown backyard. Reflecting on how Harvard handled its proximity to chaos, Garber said he had “never seen anything quite like the events of Marathon week.” “It makes you realize that this is an incredible community,” said Garber. “When it really matters, people pull together, time and again.”

—Staff writer Madeline R. Conway can be reached at mconway@college.harvard.edu.

Follow her on Twitter @MadelineRConway.

—Staff writer Nikita Kansra can be reached at nkansra01@college.harvard.edu.

Follow her on Twitter @NikitaKansra.