St. Augustine, FL- A leaking propane gas tank exploded in a garage Monday at a four-unit townhouse, shifting the units an inch off the foundation, according to St. Johns County Fire Marshal Frank McElroy.

“The explosion blew the garage door across the street,” McElroy said.

He said a man was cooking spaghetti with a propane grill outside his home at 725 Middle Branch Lane in Julington Creek about 4:30 p.m. McElroy said the power was out in the house, but came back on while the food was cooking.

The man moved the grill into his garage and went inside the home. McElroy said propane gas was still leaking and a spark from the hot water heater may have ignited it.

“A fireball came in and burned the man, singed his eyebrows,” McElroy said. He said the side wall in the man’s garage shifted about 6 inches outward while the four-unit townhouse moved about an inch on the foundation.

The man suffered first-degree burns and was treated at the scene. Estimated damage to the home and surrounding townhomes was still under investigation. McElroy said an engineer will determine if the townhouse has to be rebuilt.

McElroy said the electrical wiring may have been damaged when the townhouse shifted, so the power has been shut down there.