A 4-year-old boy was killed in a two-alarm house fire in Chester Friday night, authorities said.

An 18-year-old babysitter in the house suffered injuries and was taken to Crozer-Chester Medical Center, according to Chester Battalion Chief Jack Powers. Fire officials were unable to interview her as of 11 p.m. because of the severity of her injuries, authorities said.

The fire broke out in the 1100 block of Terrill Street around 8 p.m., authorities said. The fire was under control around 8:45 and was under investigation.

Powers said that when fire crews arrived, the first floor was fully involved and flames were coming out of the second floor.

"We got a report that a child was still trapped," Powers said. Firefighters got to the second floor and found the boy's body in a front bedroom.

Powers said six other members of the boy's family lived in the rental home, which was gutted.

About 10:50 p.m., a woman arrived and collapsed in tears. She was helped to a house down the street.

An adjoining house was also damaged by flames.

A man who declined to give his name said people in the neighborhood tried to find a way through the flames in hopes of finding the boy.

"People said they were going in, but it was too much fire," he said.

Contact staff writer Robert Moran at 215-854-5983 or bmoran@phillynews.com.