Zachary S. Larrabee, 31, of College Avenue, was arrested on charges of aggravated assault and criminal threatening in the attack that closed down Union Street Thursday and spurred a heavy police response.

The three-day trial of Andrew Seamon, 49, ended Thursday at the Capital Judicial Center.

Police said when they stopped Derek Gauthier on Silver Street on a warrant, they also found prescription drugs and marijuana, and he was charged with several counts.

Police said a man, reportedly armed with a gun and a hammer, fled the scene after hitting a man in the head Thursday morning in a Union Street apartment.

Police credited a passer-by with reporting the blaze, which firefighters quickly extinguished.