Heat and 20-mph winds Thursday whipped a couple of small brush fires near Temecula into a blaze that destroyed 100 acres and threatened to spread and consume 10 times as much acreage, authorities said.
The blaze in steep slopes between De Luz and Temecula was only 10% contained by late afternoon and conditions made it unpredictable, said Jody Hagemann, a spokeswoman for the Riverside County Fire Department.
"It depends on the weather cooperating," she said. "With the heat and wind, there's potential for 1,000 acres" being burned.
More than 350 firefighters were on the scene and dense smoke covered the entire French Valley, forcing some late-afternoon road closures.
By evening, the fire was burning in the direction of Murrieta, authorities said.
Several commercial properties in the area were evacuated but no homes were threatened, Hagemann said. The cause of the fire was under investigation.