A 13-year-old boy was hit by a stray bullet Wednesday night while in his Chelsea apartment bedroom, police said. 

Authorities said the boy was sitting in his third-floor apartment on Bellingham Street just after 8 p.m. when the bullet struck him in the shoulder.

He was taken to Massachusetts General Hospital, where he is recovering from surgery and is in good condition, according to Capt. Keith Houghton.

The incident caused the nearby Bunker Hill Community College's Chelsea campus to be locked down for about a half an hour, according to the school's Twitter account. 

Houghton said detectives are making progress on the case based on evidence left at the scene.