Marquette, MI – (AP) — A disconnected propane line is the likely cause of an explosion in a cottage on Lake Kawbawgam.

The explosion occurred Thursday afternoon as the owner was opening the cottage for the summer, said Gary Johnson, chief of the Chocolay Township Fire Department. Johnson declined to release the owner’s name.

“The cottage is a family camp and the owner did not know there was a propane line running from the sauna to the cottage,” Johnson said. The sauna is heated by propane, but the cottage had been converted to natural gas. However, the propane line was still present in the cottage, he said.

“When the owner turned the thermostat on in the cottage, the initial ignition of the furnace is what is believed to have caused the explosion,” Johnson told The Mining Journal. “It’s still under investigation, but it was an accident. We don’t believe foul play was involved.”

The explosion lifted the 1,200 square-foot structure about three feet off its foundation and knocked it two feet on one side, he said. The owner, who was inside, was uninjured.

“There was a wall in between him and where the explosion ignited,” Johnson said. “He heard the initial rumbles and hit the floor. He’s very lucky.”

Damages are expected to total several thousand dollars, Johnson said.