WESSINGTON SPRINGS - State fire officials on Wednesday said a leaky propane line likely was the cause of an explosion that injured one man and destroyed three homes last week.

State Fire Marshal Al Christie said a propane line in the crawl space of Darrick Van Dyke's residence apparently was leaking and found an ignition source.

"We are leaning toward (that cause)," said Christie. "There was a failure in the line itself and that is what we are following up on."

Van Dyke was flown from the Wessington Springs airport to Hennepin County Medical Center in Minneapolis. His family said he sustained third-degree burns on his legs and remains hospitalized. Van Dyke was the only person injured in the blast.

The Van Dyke home and two adjacent homes, both unoccupied, were destroyed by the explosion.

Christie said the propane could have come into contact with various ignition sources, such as a furnace pilot light or static electricity. It's unlikely the ignition source will ever be pinpointed, he added.

Christie said such an explosion is rare in South Dakota, but residents should have their heating appliances checked if they have any concerns.

He said smell is usually the best indicator there might be a problem.

"Whether it's natural gas or propane, if you have a concern about your heating appliance, go to your heating fuel dealer and have them check your system out," he said. "It's probably something that you would not be able to see."