Harvard University Police have released photos of suspects they want to question in connection with the explosion at Harvard Medical School.
The grainy photos were captured on surveillance cameras.
The photo release comes as police say they saw two "unidentified individuals fleeing from the building," according to NBC News. Complex has reached out to Harvard University police for additional details.
According to NBC News, a fire alarm alerted authorities to the situation at 2:48 a.m. at the Goldenson Building on the Harvard campus.
"The officer attempted to stop the individuals before proceeding to the floor where the alarm had been triggered," police said in a news release, according to USA Today.
According to CBS News, when police responded to the fire alarm, they discovered "an explosion had happened on the fourth floor."
Authorities are operating under the belief that the explosion was an "intentional act."
"We're assisting our partners at the Harvard University Police Department and we're going to decline further comment at this time. We'll refer to the Harvard University Police Department," the FBI told CBS News.
Authorities did not release the type of device that caused the explosion, but a sweep of the building did not unearth any further explosive devices, according to Boston.com.
The people being sought by police for questioning were wearing sweatshirts and face coverings.
The motive was not released. The Boston Fire Department Arson Unit responded to the scene, according to Boston.com. No one was injured.
What is the Goldenson building? "The site is named for Leonard H. Goldenson (1905-1999), president of the American Broadcasting Company, and his wife Isabelle Charlotte Weinstein Goldenson (1921-2005), co-founders of United Cerebral Palsy, the charitable organization," according to a Harvard Planning website.
"The Goldenson Building was designed for Harvard Medical School by Shepley, Rutan and Coolidge of Boston and opened in 1906," it adds.