CHICAGO (CBS) — A woman was killed and three men were injured, including a firefighter, after a vacant building caught fire Thursday night in the Logan Square neighborhood.

CBS 2’s Marissa Bailey reports the woman and two men apparently were squatting in a vacant two-story building in the 3400 block of West Armitage Avenue, when a fire started in the second-floor apartments around 11:40 p.m. Thursday.

A woman was transported to Norwegian American Hospital, where she was pronounced dead shortly after midnight, according to Fire Department spokesman Larry Langford.

Two men were taken to John H. Stroger Jr. Hospital of Cook County; one was in critical condition, the other man’s injuries were not considered life-threatening.

The victims’ identities have not been released.

A firefighter “twisted his arm” while helping put out the fire, and was taken to a hospital, but was immediately released, according to Langford.

Officials said the building, which has commercial space on the ground floor, has been vacant for six months. Fire officials said they believe the victims were squatting.

The cause of the fire was under investigation.