LOWELL, Mass. (AP) — Investigators say a fatal four-alarm blaze in Lowell was caused by a man using a plumbing torch to make repairs in a second-floor bathroom.

Authorities found the body of a man who perished in the blaze on Wednesday morning almost 12 hours after the fire was reported.

Fire Chief Edward Pitta and state Fire Marshal Stephen Coan say an autopsy is scheduled, but the victim is believed to be the man who was using the torch.

His name was not immediately released.

Firefighters tried to get to the man Tuesday afternoon but were beaten back by the flames.

The building had a store on the ground floor and apartments on the upper two floors.