About 1,500 people were allowed to return home Thursday, a day after butane (search) fumes from a wrecked tanker truck caused explosions in at least two homes.

The driver of a van was hospitalized in serious but stable condition after his vehicle was broadsided by the tanker Wednesday on U.S. 89 in Kaysville, about 20 miles north of Salt Lake City.

Truck driver Travis Mortensen, 25, who was hauling about 12,700 gallons of the highly flammable gas from a refinery, said his brakes went soft and he could not stop at a red light.

Heavier-than-air fumes leaked from the tanker and flowed downhill to a home where they were ignited, possibly by a pilot light, sheriff's Capt. Kenneth Payne said.

The blast blew out windows and wallboard, and flames shot back to the tanker and set off the fuel there, sending fire 100 feet into the air, officials said.

An explosion of butane fumes also blew out windows in a second home, Payne said, and police were trying Thursday to confirm reports of a third explosion.

"We're just glad we took the precaution of evacuating these people before these things occurred," sheriff's Lt. Randy Slagowski said.

The butane had burned off by early Thursday, Slagowski said, and the trailer was hauled away. Police said the burned cab may make it impossible to confirm the tanker driver's story of bad brakes.

Most of those evacuated went to the homes of friends and relatives, Fruit Heights City Councilman DeeEll Fifield said.