GLADWYNE, Pa. — An apparent gas explosion leveled an empty mansion in an affluent suburb of Philadelphia on Sunday, reducing the 9,000-sq. foot (836-sq. meter) home to rubble and frightening neighbors and others who felt the thunderous boom.

The explosion at the Gladwyne mansion happened just after 8 p.m., and was felt as far away as southern New Jersey.

The house was undergoing extensive renovations, authorities said, and no one was inside the home at the time of the explosion. It was reduced to a few walls and rubble, as various debris ended up strewn among nearby trees.

The family was staying in a second residence when the mansion exploded. Their names have not been released.

A spokeswoman for PECO Energy Company said no injuries were reported. The cause of the explosion remained under investigation Monday.

Peter Cooke, who lives across the street from the home, told The Philadelphia Inquirer that he was reading a book when the explosion occurred. The 80-year-old Cooke said he had never heard something that loud, but when he looked outside, he couldn't see fire.

Cooke's son, Michael, compared it to a meteor strike.

Steve Liebowitz, 60, who lives about a half a mile away, said the boom sounded as if it was right in his backyard and he initially feared his outdoor grill may have exploded before he realized what had happened.

"We were actually afraid," he said. "In today's world, you don't know what kind of explosion happened or whether it was a gunshot."

The fire marshal and the Bureau of Alcohol, Tobacco, Firearms and Explosives are investigating.