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 — There was an explosion early Saturday at Harvard Medical School that appears to have been intentional, but no one was injured, authorities said.

A university police officer who responded to a fire alarm tried to stop two unidentified people who ran from the Goldenson Building before going to where the alert was triggered, university police said in a statement.

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.

Police released grainy photos of two people wearing face coverings and what looked like sweatshirts.

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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