BOSTON >> 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

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