The house was believed to be vacant, and no one was injured, officials said. Neighbors said the house had been under construction for a while.
Southern California Gas Company officials shut off the main gas line after flames were spotted shooting up from a line near the house. Firefighters picked through the rubble with the aid of a cadaver dog -- just in case -- but found no one inside.
"It's unfortunate someone's house blew up, few houses were damaged," said Riverside Fire Department Capt. Bruce Vanderhorst. "But we're also very relieved that no one was injured, and no firefighters were injured."
Officials have yet to confirm the cause of the explosion, but have ruled out foul play.