The 17-year-old girl was the first one to notice the flames.

She had been sleeping in the living room inside the double-wide mobile home in rural Marietta, Oklahoma, early Wednesday morning when she woke up and saw the fire, Sheriff Marty Grisham said. She managed to escape without getting hurt, KTEN 10 reported.

A neighbor told KXII 12 she ran to his home to ask for help.

“The daughter is coming, knocking on my door and when I see it I'm scared because I don't know what's going on,” said Francisco Sanchez.

The girl’s 13-year-old brother had also been sleeping in the living room, where authorities believe the blaze started — but he didn’t flee the home. Instead, the boy rushed to his 60-year-old father, who is paralyzed, and tried to get him into a wheelchair, KXII 12 reported.

“This family is just sleeping and the son is doing what he can to protect and save his dad,” Grisham said.

Deputies and firefighters arrived to find the house engulfed in flames, Grisham said, according to the news station. But they couldn’t get to the boy and his father because the blaze was so intense.

By the time firefighters managed to put out the fire, it was too late. The boy and his father, identified as James Cummins, were overcome by the heavy smoke, The Daily Ardmoreite reported. The boy had died trying to save his dad, Grisham said.

The children’s mother had been at the store, KXII 12 reported. Sanchez told the news station she was devastated when she returned.

Fire investigators say the blaze was an accident. Space heaters in the living room may have been to blame, the Associated Press reported. Officials believe the boy and his sister had been sleeping near it to stay warm that night, KTEN 10 reported.

Temperatures were below freezing, according to the Weather Channel.

The boy has not been identified by authorities.