A 64-year-old man was killed Wednesday in a house explosion in Pittsburg suburb. He was babysitting for his 4-year-old granddaughter who escaped with a few injuries, which are not life-threatening. The girl was taken to Children’s Hospital of Pittsburgh.

Neighbor Lynn Celia said that she ran across the street and found the 4-year-old girl sitting in debris near the house next door. She tried to rescue the old man, but she could not find him.

“The smoke was so thick, you couldn't see anything," she said. "You couldn't even breathe.”

Elmore Lockley, a spokesman for the Dominion Peoples natural gas utility said that the explosion was caused by natural gas. He said that there has not been reported a gas leak, but gave assurances that investigators will examine pipes and appliances inside the house, the USA Today reports. However, it is not clear yet what had happened.

Pieces of burnt insulation and debris were scattered over a 1,000-foot area. The explosion was so powerful that it damaged 14 other houses in Plum Borough neighborhood Wednesday afternoon. More than forty residents were evacuated.

The man killed in the explosion was Richard Leith. His granddaughter, Gianna Pettinato has miraculously survived the explosion. Plum Borough Police Chief Frank Monaco said Gianna had a broken femur.

The Associated Press informs that a school located close to the suburban Pittsburg home was cleared out because of a gas leak. Adlai Stevenson Elementary School in Plum borough was evacuated Thursday morning, police say. Plum borough is 15 miles from Pittsburg. The National Transportation Safety Board will also investigate.