Fifty residents of a halfway house in Paterson have been displaced by a five-alarm fire that sent thick black smoke into the sky Saturday morning.

Officials say there are concerns for the structural integrity of the remainder the Straight & Narrow facility at 508 Straight St.

Firefighters were focused on the back of the building where some propane tanks were being stored. One of the tanks exploded during the incident.

After hours of fighting the blaze, firefighters were able to get it under control. They say they will be concentrating on hot spots.

The building was home to about 50 men in recovery. Authorities say all of them are accounted for, but staff at Straight & Narrow say the residents have lost everything.

Fire officials say the building will need to be demolished.

An elementary school on Dell Avenue is being used as a temporary shelter. It is not yet clear what sparked the fire.