A powerful explosion destroyed a house early Wednesday, killing a woman and her young grandson and seriously burning two of her sons, officials said.

More than a dozen other homes were damaged, and an 88-year-old neighbor was treated for cuts.

Utility workers and the state fire marshal's office were still working to verify the cause, but Police Chief David Haley said his department was treating it as a natural gas explosion. Residents of the house and other people in the area had reported smelling gas.

The explosion at about 7:30 a.m. left a crater filled with charred, splintered wood where the house had stood. Debris was hurled as far as a block away in all directions, and two vehicles parked nearby were blackened.

Bob Eskew, who lives a couple of houses away, said he was working on a computer when he "heard two loud explosions, kind of like an F-16 flying over real low." His house shook and some of his front windows shattered.

Leigh Morris, a spokesman for St. Louis-based Ameren Corp., the supplier of natural gas and electrical service in the area through its AmerenIP subsidiary, said the company had reviewed its records and received no reports of anyone calling about a suspected gas leak in the neighborhood.

He said that Ameren would leave it up to state authorities to determine the cause of the blast, but that utility employees were assisting in the investigation.

Police identified the dead as 55-year-old Margaret Hatlen, whose body was found in the basement of the destroyed home, and her 9-year-old grandson, Michael Albracht.

Her 27-year-old son had burns over 30 percent of his body, and a 15-year-old boy was severely burned, Haley said. Both were taken to Memorial Hospital's burn center in Springfield, about 55 miles away.

Carlinville is a community of 5,800 people about 60 miles northeast of St. Louis.

Later Wednesday, at least 13 firefighters were injured when a two-story house exploded in Constantia, 15 miles northeast of Syracuse, N.Y. The homeowner wasn't hurt.

The explosion, which ignited while firefighters were battling a blaze at the home, sent one firefighter flying out a door, two others rolling out a window, and a fourth stuck beneath a fallen rock wall, neighbor Matthew Whaley said.

"I was dumping cold water on a guy whose skin was coming off his forehead and his mustache was melted to his face," Whaley told The Post-Standard in Syracuse.