Pennsylvania ? Fire swept through a house in southwestern Pennsylvania early Saturday, killing six young children and a woman and injuring one other person, state police said.

Several people in the house were able to escape, state Trooper Brian Burden said.

Police said the young victims were four girls ages 4, 9, 7 and 10, and two boys ages 2 and 3. Authorities said the woman was the mother of three of the children.

Robert Husner, who was staying in the home, said Joshua Arthur Sr., the father of three of the children, woke him and the two of them tried to rescue all six children, who were sleeping in at least two rooms.

The home’s gas furnace was not working so the residents were using space heaters throughout the home to keep warm, Husner said. Authorities said it was unclear whether they contributed to the fire, which was being investigated by a state police fire marshal.

State police identified the victims as Rebecca Eddy, 26, and her children Tiffany Blake, 10, Rebecca Blake, 9, and Diamond Blake, 7; and Arthur’s children, Donna Jo Arthur, 5, Joshua Arthur Jr., 3, and Christopher Arthur, 2. Arthur was listed in serious condition at Mercy Hospital in Pittsburgh. Husner and two other people escaped from the flames, authorities aid.