PITTSBURGH – Fire raced through a three-story row house early Tuesday, killing five children, and authorities said they were looking for a teenage baby sitter who was supposed to be watching them.

Neighbor Sontaya Perry, 22, said she could hear the children inside the house screaming as the fire raged from the windows before dawn. She said she tried to get in, but the wooden steps leading to the door were in flames.

“They were screaming, and five minutes later they stopped screaming,” Perry said.

On the street outside, two boys were begging for someone to help for their brothers and sisters, she said.

The victims, ages 2 to 7, were all found on the second floor, authorities said. One was dead on arrival at West Penn Hospital and two others died in the emergency room, said Stephanie Waite, a hospital spokeswoman. The Allegheny County Medical Examiner’s office said it had the bodies of a boy and a girl.

Two other children were taken to hospitals; their conditions were not immediately released.

Police were looking for the baby sitter who apparently was supposed to have been watching the children, said Pittsburgh police spokeswoman Diane Richard. Authorities said as many 12 people from two families may have been living in the home.

Tuesday morning, investigators were inside the gutted and blackened house skeleton of the home, examining what remained. Officials said flames had been shooting from all three floors of the building in the city’s East Liberty section when firefighters arrived around 1:20 a.m., and the blaze also damaged a vacant building next door.