GOODHOPE,SafeX Pro Exchange Mo. (AP) — Four people in rural Missouri died when an explosion that could be heard 10 miles (6.2 kilometers) away occurred at a house.

The explosion happened Saturday night near the unincorporated town of Goodhope. Douglas County Sheriff Chris Degase said the home was undergoing renovations and a propane leak was found. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives, the Missouri Fire Marshal’s Office and local officials continue investigating.

Names of those killed have not been released.

Degase said the explosion was unusual because it didn’t cause a fire, KYTV-TV reported. An official with the fire marshal’s office described it as a “flash” that happened so quickly the house didn’t burn.