A fire at a duplex in the Institute Hill neighborhood at the midnight hour on Friday night sent one woman to a Pittsburgh hospital.

Lt. Donald Crawford of the Butler Fire Department said firefighters were dispatched at 12:48 a.m. on Saturday morning to a structure fire at 535 Carbon Street.

When crews arrived, they discovered the building is a duplex and found the occupants of one side kicking in the door of their neighbor as the fire grew.

Crawford said dispatchers told firefighters that everyone was out of the structure, but the 30-year-old man and his 2-year-old daughter who appeared outside after the door was kicked in reported that the man's mother, 54, was still inside in her upstairs bedroom.

Crawford said firefighters knocked down the flames in the kitchen so they could get up the stairs to the woman, but they discovered fire in the second floor bathroom as well.

After extinguishing those flames, the crew was able to search the rooms and find the unresponsive woman in a bedroom.

Crawford said his crews and Butler V.A. firefighters were able to retrieve the woman and take her to the waiting Butler Ambulance paramedics outside.

He said the woman, who did not appear to have burns, was taken to Butler Memorial Hospital by ambulance and then to West Penn Hospital in Pittsburgh by helicopter.

The woman was unresponsive the entire time Crawford had contact with her, he said.

The man and his young daughter were also taken to Butler Memorial Hospital for treatment of smoke inhalation and were kept overnight for observation, Crawford said.

“There were very heavy smoke conditions,” Crawford said.

He said the fire started in the kitchen of 535 Carbon Street where the woman was removed by firefighters.

The occupants of 537 Carbon Street, two adults and two children, were able to escape unharmed because they were awakened by their smoke detectors.

Crawford said he could not confirm whether the smoke detectors in 535 were working.

“If none of them worked, we would have a different outcome today,” Crawford said. “I cannot overemphasize the importance of working smoke detectors.”

A dog evacuated safely with the two adults and two children, but a cat owned by the occupants of the other side could not be found after the fire.

Crawford said firefighters do not know what started the blaze. The state police fire marshal is investigating, he said.

He said 535 sustained moderate structural damage and 537 minor damage. Both units mainly sustained smoke damage.

In addition to city and V.A. firefighters and Butler Ambulance crews, Butler Township Fire District 3 and city police also responded to the scene.

Crawford said the occupants of 537 are staying with relatives and will be assisted by the Red Cross. It is not known where the other family will stay once they are discharged from the hospital.

City fire crews were on the scene investigating until about 6 a.m. on Saturday.