BOSTON — Federal authorities have arrested a Massachusetts man who they say threatened to assassinate President Barack Obama, bomb several police stations and attack a mosque.

Forty-year-old Joseph Garguilo appeared in Boston federal court on Monday to face a single charge of possessing ammunition, which violated the terms of a recent restraining order filed by his ex-wife.

The FBI arrested Garguilo on Friday after a raid of his Holliston home allegedly turned up assault rifle parts, incendiary materials, ammunition and handwritten notes threatening violence against Muslims.

Believing he was “about to snap,” Department of Justice officials say a friend reported Garguilo’s behavior. A neighbor told The Boston Globe that Garguilo’s a “bad dude.”

Garguilo was ordered held without bail pending a hearing Wednesday. His attorney denied he threatened anybody.