Fire swept through a two-story house early Friday, killing a teenager and her three young children in an upstairs room, a fire official said. The youngest victim was 2 weeks old.

The teen's father and five other people escaped.

Authorities believe the pre-dawn fire was caused by a space heater, said Doug Smith, a Fire Department battalion chief.

"This is one of our nightmares here is to come on the scene and have this many people trapped," Smith said.

Ten people were inside when the fire started.

The teenager's father, Paul Sadler Sr., said he smelled smoke and tried to save his daughter and her children, but it was too difficult.

"I tried to get into the bedroom. I couldn't get in," he said before being overcome with emotion and turning away from reporters.

Smith identified the dead as Mindy Hanners, 19; Katelynn, 4; Austin, 1; and Nevaeh, 2 weeks.

Two firefighters were treated for burns.

The exterior of the century-old home was still standing, but everything visible through a broken window was charred, and the home's white siding was blackened where flames came through the windows.