GROVE CITY — Borough and state fire officials are still trying to determine the cause of an early Friday morning house fire that cost a woman her life.

Patricia Andrews-Smith, 40, of 132 Garden Ave. was identified as the fire victim by Mercer County Coroner J. Bradley McGonigle III late Friday afternoon.

An autopsy is pending.

Neighbors said they heard crackling and snapping from the fire about 6:30 a.m. Friday. The fire leveled the duplex on the city's east side.

Andrews-Smith, who lived on one side of the duplex with her dog and long-time boyfriend, initially escaped the blaze with her boyfriend and an unrelated woman and her son from the other side of the duplex.

Witnesses say Andrews-Smith ran back into the house to rescue her dog but did not escape the flames a second time.

Two Pine Township firefighters who went into the house to try to rescue her suffered burns, said Jeff Nicklin, a township firefighter and former chief.

Brad Holmes, 21, suffered burns over 75 percent of his body, according to officials at UPMC Mercy Hospital in Pittsburgh. He was in critical condition Friday night.

Firefighter Scott King suffered injuries described by Nicklin as moderate. He was treated and released Friday afternoon from UPMC Mercy Hospital.

Other fire departments at the scene included Grove City, Harrisville, Slippery Rock, Springfield, Mercer, Stoneboro and Jackson Center.

In a Friday news release, Chief Dean Osborne of the Grove City police said the house was completely in flames when his officers arrived Friday morning.

Grove City Fire Chief Jeff Badger said frigid temperatures froze hydrants while firefighters fought the blaze. He agreed the fast-moving fire had engulfed the home by the time the first emergency responders arrived.

While tucked into a neat residential section of the city, the duplex was not too close to neighboring houses, although the siding on one house did melt.

Grove City firefighters remained on the scene throughout the day, working with Cpl. Gary Sawor, a state police fire marshal with the Mercer barracks, who picked through the ashes of the duplex with a pitchfork, looking for the fire's source. He has yet to issue a report.

Two Dominion Peoples' gas company investigators stood in the snow across the street from the debris, waiting for police and fire officials to grant permission so they could investigate the fire.

Small white gas line flags dotted a grass strip along the street in front of 132 Garden, and neighbors say about 12 days ago the area smelled of gas.

Dominion is checking the fire scene to see if natural gas played any part in the tragedy.

As of Friday afternoon, authorities had not released the names and whereabouts of the other three duplex residents.