Police now suspect the Staten Island house fire that killed a mother and her four children early Thursday morning was a murder-suicide, and fire officials believe the blaze was intentionally set.

Fire officials say the blaze broke out around 4:15 a.m. on the top floor of a house at 302 Nicholas Avenue in Port Richmond. The fire quickly spread to the roof and took about an hour-and-a-half to bring under control.

When firefighters arrived, they found Leisa Jones, 32, and her children, C.J., 14, Brittany, 10, and Melanie, 7, with their throats slashed.

Jones' youngest child, Jermaine Sinclair, 2, did not have his throat slashed, but died at the hospital.

Police believe the troubled 14-year old, who had a history of setting fires, was responsible for it all.

A straight-edge razor was found underneath his body.

The city medical examiner's office told the Associated Press that autopsies on all five victims will be held on Friday.

Neighbors who spoke with NY1 at the scene say they are shocked.

"He [C.J.] was great with my kids, he was great with his sisters; I couldn't really say but I know I didn't see any problems with the kid," said one neighbor.

"She was a very good mother and all her kids so I don't see why he would do that; I really don't," said another.

"C.J. was the most loving boy in the world. I don't believe that he did anything like that, he's not capable of doing anything like that; he loves his mother and his brother and his sisters too much," said a third.

Police Officers Mashiel Santo and Edward Murphy, who were patrolling the area due to the recent spike in hate crimes, smelled smoke, rushed over to the burning house and were able to help pull three other families to safety.

Residents on the first floor said they had smoke detectors, but they did not go off. They also said they heard popping noises before the fire broke out.

"It's a tragedy. It's a tragedy. It's sad. It's really sad," said one person rescued from the flames. "It could have happened to any of us. If they didn't come bang on the door, would we be alive right now?"

"I got my kids out, thank God," said another. "I used to come home, the kids would be outside. The little two-year-old was cute."

"The flames were actually coming from her side into my bathroom window, so I ran to the back and woke my wife up and then I got the kids and at that time the cops were already knocking on the door," said a third.

Earlier in the day, the fire commissioner had noted there were no smoke detectors on the floor where the family lived and New York City Fire Department officials had distributed smoke detectors in the neighborhood.

Meanwhile, Anthony Cassieri, a Brooklyn funeral home owner who lives in Bulls Head, Staten Island, was so moved by the story of the fatal fire that he is donating full funeral services for the five victims and paying for all expenses.

Cassieri said he heard the sirens from the fire and was upset to learn about the loss of life.

"If they couldn't afford one funeral, how could they afford five? Who could afford five funerals today? It's expensive, it’s difficult, it’s definitely a tragedy,” he said. “When we learned there were four children, it makes it even worse, you know. You lost a whole family."

Dates for the services at the Brownsville funeral home have not been set.