Less than twenty-four hours after two bombs exploded near the finish line of the Boston Marathon, killing at least three and injuring at least 176, government officials and investigators met the media at a hotel near the blast zone to report that the investigation of the bombings is ongoing and rapidly growing in scope.

Massachusetts Gov. Deval L. Patrick ’78 led a press conference Tuesday morning that included Boston mayor Thomas M. Menino, U.S. Senator Elizabeth Warren, and Boston Police Commissioner Edward F. Davis, who announced an updated casualty count: 176 wounded—17 of them critically—and three dead.

Davis said that the finish area had been swept for explosives on two occasions Monday morning, both hours before the explosions. Asked by a reporter why those searches had not turned up any devices, he said that because of the length of the racecourse, “people can come and go and brings items in and out.”

Rick DesLauriers, the FBI Special Agent-in-Charge who is leading the investigation into the incident, also refused to speculate on why the bomb sweeps failed to detect the explosives. Additionally, he would not reveal if the FBI is guarding any potential suspects, as was reported widely yesterday. DesLauriers did say that the investigation is ongoing and that “there is no known imminent threat.”

Officials at the press conference also rejected reports that spread rapidly yesterday alleging the discovery of as many as five additional explosive devices.

“Responding to rumors—there were reports out there that there were seven devices—that is not true,” said Gene Marquez, an agent with the Bureau of Alcohol, Tobacco, Firearms, and Explosives. “I think [those reports] happened as a result of some suspect packages that were disrupted. But we only have two devices that we are aware of. Both those devices were the ones involved in the explosive incident.”

—Staff Writer Matthew Q. Clarida can be reached at clarida@college.harvard.edu. Follow him on Twitter @MattClarida