This photo provided by the Harvard University Police Department shows...

This photo provided by the Harvard University Police Department shows a person of interest in an explosion at the Harvard Medical School in Boston, on Saturday, Nov. 1, 2025. Credit: AP/Uncredited

BOSTON — A Harvard Medical School building has reopened while a “very active” investigation continues into a weekend explosion that authorities said was intentionally set off.

An officer who responded to a fire alarm early Saturday morning encountered two people running from the Goldenson Building, according to university police. The explosion occurred on the fourth floor of the building, which houses labs and offices associated with the medical school's Department of Neurobiology.

The Boston Fire Department determined that the explosion was intentional and officers did not find additional devices in a sweep of the building, police said. No one was injured.

“The small section of the fourth-floor hallway where the explosion took place has been cleared and is fully operational. There was no structural damage to the building, and all labs and equipment remain intact,” medical school officials said in a statement.

An FBI spokesperson declined to comment Monday other than describing the investigation as “very active.” Police released grainy photos of two people wearing face coverings and what looked like sweatshirts.

In recent months, President Donald Trump has targeted Harvard with a series of investigations and billions of dollars in funding cuts as it presses for changes to its policies and governance.

Suffolk County Sheriff Errol Toulon Jr. spoke with NewsdayTV's Ken Buffa about what life is like for the Gilgo Beach serial killer Rex Heuermann in jail. Credit: Anthony Florio; File Footage; Photo Credit: Newsday / James Carbone, John Paraskevas; AP / David Bookstaver, Clark County Sheriff's Office, Richard Drew, Mitchell Tapper, Don Ryan; Peconic River Sportsman’s Club / Kerry Goldberg

'He will be ... coming out of prison in a body bag' Suffolk County Sheriff Errol Toulon Jr. spoke with NewsdayTV's Ken Buffa about what life is like for the Gilgo Beach serial killer Rex Heuermann in jail.

Suffolk County Sheriff Errol Toulon Jr. spoke with NewsdayTV's Ken Buffa about what life is like for the Gilgo Beach serial killer Rex Heuermann in jail. Credit: Anthony Florio; File Footage; Photo Credit: Newsday / James Carbone, John Paraskevas; AP / David Bookstaver, Clark County Sheriff's Office, Richard Drew, Mitchell Tapper, Don Ryan; Peconic River Sportsman’s Club / Kerry Goldberg

'He will be ... coming out of prison in a body bag' Suffolk County Sheriff Errol Toulon Jr. spoke with NewsdayTV's Ken Buffa about what life is like for the Gilgo Beach serial killer Rex Heuermann in jail.

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