Ted Docks, Special Agent in Charge Federal Bureau of Investigation Boston Division, speaks to reporters during an announcement of the arrest of two people in the November 1, 2025 explosions at Harvard University’s Medical School campus, along with Denis Downing, Interim Chief of the Harvard University Police Department, and Leah Foley, United States Attorney for the District of Massachusetts, at the federal courthouse in Boston, Massachusetts, U.S., November 4, 2025. REUTERS/Brian Snyder

By Nate Raymond

BOSTON (Reuters) -Two Massachusetts men visiting Boston area colleges on Halloween night when numerous parties were underway have been arrested and charged with causing an explosion over the weekend at Harvard Medical School's campus, authorities said on Tuesday.

Federal prosecutors alleged that Logan Patterson, 18, and Dominick Cardoza, 20, broke into a building housing Harvard research labs early Saturday morning and caused an explosion with a commercial firework that drew national attention.

Police and the Federal Bureau of Investigation on Saturday announced they were investigating what the Harvard University Police Department said appeared to be an "intentional" explosion.

"Anxiety levels naturally rise when the public learns that an explosion was intentionally caused," U.S. Attorney Leah Foley told reporters during a press conference.

Ted Docks, head of the FBI's Boston division, said no one was hurt and property damage was limited, but he noted that "setting off an explosive device inside a locker at an institution geared toward higher education is not some harmless prank."

Lawyers for Patterson, of Plymouth, Massachusetts, and Cardoza, of Bourne, Massachusetts, could not be immediately identified.

According to charging documents, surveillance cameras captured two men later identified as Patterson and Cardoza shortly after 2 a.m. on Saturday walking toward the Harvard Medical School campus while wearing face coverings.

Surveillance video showed them lighting Roman candle fireworks, climbing over a chain-link fence, entering a construction area surrounding Harvard's Goldenson Building and then climbing scaffolding to access its roof, charging papers state.

Harvard police minutes later received an alert of a fire alarm from an explosion on the building's fourth floor, which houses a laboratory within the school's Department of Neurobiology. The men then fled.

Authorities said the explosive detonated in a locker and is believed to have been a large, commercial firework.

Surveillance video captured Patterson after the explosion at Wentworth Institute of Technology in Boston and recorded him later meeting up with Cardoza.

Students at Wentworth told investigators that both men had gone there earlier in the night for Halloween social activities and told some of them about their involvement in the explosion, according to court documents.

(Reporting by Nate Raymond in Boston; Editing by Richard Chang)