PITMAN, N.J. (AP) — Fire officials say five firefighters have been treated or assessed after injuries battling a blaze in New Jersey.

The fire in the three-story duplex in Pitman, Gloucester County was reported shortly before 1 p.m. Sunday.

Officials said three firefighters were injured when a staircase into the basement of the building collapsed. The extent of their injuries wasn't immediately available.

Two other firefighters were being assessed by medics, but the reason wasn't immediately available.

The cause of the fire is under investigation.