From left to right, SSP proctors BENJAMIN T. SIRACUSA ‘03, ALEXANDRA N. YURKOVIC ‘04 and GITA A. RAO ‘03 clean up a barbeque yesterday in front of Straus Hall, the site of vandalism on Monday.

Two vandals snuck into Straus Hall in Harvard Yard on Monday, starting a fire in the basement and defecating on the fourth floor of the summer school dorm.

The two male intruders gained entrance by following a Secondary School Program (SSP) student into the Straus A entryway, said Dean of Summer School Student Christopher S. Queen.

Before they entered the building, Straus residents said they noted that the two were acting strangely outside.

“The two perpetrators...started asking if they were at Boston College,” said Straus resident Ohyoom Kim, who was outside at the time. “They were holding Budweiser cans, and asking what the dorm rooms were being used for.”

“They were chasing students around in front of the dorm, trying to get inside,” added Emily E. Lancaster, who witnessed the scene from her fourth floor Straus dorm room.

According to Queen, a student on the first floor saw the two urinating outside his window, and yelled at them to “Get out of here.” In response, the two began taunting him.

Shortly after entering the building, the two intruders defecated on the fourth floor of the entryway.

“The students found the mess before we did,” said SSP proctor Benjamin T. Siracusa ’03, who lives in Straus B. “It was on the fourth floor landing, and apparently one of the intruders covered it with a piece of paper.”

The two then proceeded to the basement of the entryway, where they set fire to some charcoal being stored there.

The interlopers are thought to have fled once the smoke alarm went off in the basement where they started the fire, according to Queen.

SSP proctor Alexandra N. Yurkovic ’04, the proctor for Straus A, spotted the two outside the building, and questioned them.

“I asked them if they were Summer School students,” Yurkovic said. “When neither of them answered, I told them to show me their I.D.s.”

The two then ran out of the unlocked gate between Straus and Lehman halls, according to Yurkovic and Siracusa.

Straus residents were evacuated from the building for two hours until midnight while Cambridge firefighters extinguished the small blaze and police conducted their investigation, Queen said. A cleanup unit later cleaned the fourth floor, as well as water from the basement’s sprinkler system.

No one was hurt in the incident, although some minor damage was done to the walls and floor of the Straus basement. The basement was closed for several days for repairs.