OKLAHOMA CITY - Investigators have ruled a fire that killed five people -- a mother and her four children -- an accident.

The fire broke out at a home at 2816 Dorchester in Oklahoma City just before dawn on Wednesday.

According to Fire Chief Randy Cornelius, seven people were inside the home. Cornelius confirmed five people died.

"When we arrived on scene we had heavy flames coming from every window and every door," said Cornelius. "[If] we had fire crews in there earlier then they should have [survived]. There was nothing anyone could do once we got there. Unfortunately."

The victims are Jeanine Bonnet, 28, Natalie Leon, 8, Samantha Leon, 7, Matthew Leon, 5, and Kara Leon, 3.

"They were really good little kids, really nice little kids," said Donald Povilonis, a friend of the family.

One person, 39-year-old Brian Poletto, was taken to the hospital. He's in critical condition at Baptist Hospital. Another victim at the scene refused treatment. All the victims were related.

Fire investigators ruled the fire as an accident. They say a space heater in the home started the fire. There were no working smoke detectors in the house at the time of the fire. Oklahoma Natural Gas (ONG) told News 9 the house had not had gas service since 2008.

The children's father, Matthew Leon, did not live with the family. He  says he doesn't have enough money to bury his kids. 

"I really worry about about Matt because he just lost everything in his whole world," Povilonis said.

Leon is asking for monetary help to give his children funerals. Anyone who wants to make a donation can go to any Bank of Oklahoma and donate money to the Matthew Leon Children's Memorial Fund.