Casper, WY – A natural gas leak caused the explosion on Thursday that knocked a grown man on his back and destroyed most of a house.

The leak came from a furnace in a crawl space of the house on 1848 Laramie Ave., said Casper Fire Prevention Officer Bob Fawcett.

“It was a fairly significant explosion,” Fawcett said. “The force of the blast blew out the front window and shot glass into the sidewalk.”

It wasn’t strong enough to damage the house structurally, but did engulf most of the inside in flames. He isn’t sure what ignited the natural gas, and said it could be any number of causes including a hot-water heater flame or a refrigerator spark.

“With natural gas we don’t always have indications from point of ignition, the fire will often flash back to where the fuel is,” Fawcett said, adding, “No one is to blame.”