Authorities are investigating what they describe as an ‘intentional explosion’ that occurred early Saturday morning inside the Goldenson Building on the Harvard Medical School campus in Boston. No injuries have been reported, but officials say the blast appears to have been deliberately set.

The Harvard University Police Department (HUPD) said the incident began around 2:48 a.m. when a fire alarm went off in the Goldenson Building, located at 220 Longwood Avenue. A responding campus police officer arrived moments later and saw two individuals fleeing from the scene. The officer attempted to stop them but was unable to do so. Shortly afterward, the officer discovered evidence of an explosion on the building’s fourth floor.

According to officials, the Boston Fire Department’s arson unit responded to assist and determined that the explosion “appeared to be intentional.” A subsequent sweep of the building by the Boston Police Department found no additional explosive devices.

Investigators from the FBI, Boston Police, and Harvard University Police are now working together to determine who was responsible and what may have motivated the attack. An FBI spokesperson said “we’re assisting our partners at the Harvard University Police Department and we’re going to decline further comment at this time.”

Surveillance footage captured two suspects inside the building prior to the explosion. University police released still images showing the individuals—both appearing to be young men with their faces covered. One suspect was wearing a brown hooded sweatshirt with “NYC” printed on the front, khaki pants, and gray Crocs. The other was dressed in a dark hoodie and dark plaid pajama pants. In other photos released earlier, one appeared to be wearing a balaclava, and the other had their hood raised with a face covering.

The Goldenson Building, which dates back to 1906, is part of Harvard’s medical campus surrounding the HMS Quad Lawn. Officials say the structure has since been deemed safe, and the investigation remains active as federal, state, and local law enforcement continue to gather evidence and review surveillance footage.

Authorities are urging anyone with information about the suspects or the explosion to contact the Harvard University Police Department’s detective bureau at (617) 495-1796.

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