Henderson, N.C. — Fire investigators believe a space heater might have started a fire that killed a 12-year-old girl and her 1-year-old brother Monday night at their Henderson home.

The official cause, however, has not been determined, Henderson Fire Chief Danny Wilkerson said Tuesday.

The blaze began around 9:40 p.m. in a back bedroom at 132 S. Elizabeth St. The two children were trapped in the room, and firefighters were unable to reach them, authorities said.

Their grandmother, Fannie Lewis, identified the girl as Abria Lewis and the boy as Joshua Chase Lewis.

Their 16-year-old brother escaped the fire, and Bernice Davis, who lives next door, said her son rescued a fourth sibling, a 9-year-old boy.

The parents, identified as Ayana and June Lewis III, had left the home briefly to go to the store, family members said. Investigators said it is unlikely any charges will be filed.

Davis said the 16-year-old told her he that was getting out of the shower when he saw smoke filling the house. He ran barefoot and screaming for help, she said.

His parents arrived shortly after, and firefighters had to restrain the father from going into the house to try to save his children, neighbors said.

The State Bureau of Investigation and the Henderson Arson Task Force are looking into the fire.

Meanwhile Tuesday, family members and friends said they are trying to cope with their loss.

"I wish it had been me instead of them," Fannie Lewis said. "I just can't believe it happened."

At Henderson Middle School, where Abria was a seventh-grade honor-roll student, classmates wrote messages to try to help comfort the family. Students also plan to wear Abria's favorite colors, purple and green, to school Thursday.

Eight-year-old Dominique Lewis said Abria, her cousin, was her best friend.

"It hurt real bad," she said. "When I first found out, I didn't know what in the world to do."

Adults said it wasn't any easier for them.

"When you lose a child, you don't ever get over it," said Queen Hawkins, a great aunt of the victims. "The only thing you can do is just pray that the Lord will strengthen you in your weakness."