Local and federal authorities are investigating an early morning explosion that rocked a building on Harvard University’s medical campus early Saturday morning, officials said.

A Harvard University police officer who spotted two people running from the Goldenson Building on Longwood Avenue around 3 a.m. shortly after a fire alarm began sounding said they tried to stop the suspects before returning to the building to see what set off the alarm, according to police.

That’s when the officer said they found signs indicating an explosion had occurred on the fourth floor. An arson team later concluded the fire had been intentionally set.

Boston police were called to the scene to sweep the building for any additional explosives but didn’t find any and the building was deemed safe.

Police say

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