Pennsylvania ? A powerful explosion flattened a house in suburban Pittsburgh on Wednesday, killing a man, injuring his 4-year-old granddaughter and damaging more than a dozen neighboring homes, authorities said.

Natural gas appeared to have fueled the explosion, a utility spokesman said, but it remained unclear why it happened.

Pieces of burnt insulation and debris were scattered over a wide area, and smoke and flames still rose from the site hours after the 1:40 p.m. blast in Plum, about 15 miles east of Pittsburgh.

“All of a sudden all the pictures blew off the walls; we heard a loud bang. It felt like an earthquake,” said Diane Fulmer, 43, who lives two houses away. Fulmer said she ran outside and “all I could see was parts of houses flying in the air.”

Richard Leith, 64, of Trafford, died at a Pittsburgh hospital, said John J. Smith, an investigator with the Allegheny County medical examiner’s office.

Neighbor Lynn Celia told reporters she ran across the street right after the explosion and found Leith’s granddaughter, Gianna Pettinato, sitting in debris near the house next door. “I could see that she had been blown out of the house,” Celia said.