Firefighters said they had checked its spread by evening, aided by calmer winds, and some evacuees were allowed back to their home. Officials said the fire was 30% contained.
Three people were in custody, accused of accidentally sparking the blaze with a campfire that police said they had used for warmth overnight.
The fire, in the San Gabriel Mountains near Glendora about 30 miles from downtown Los Angeles, started early Thursday and quickly grew to more than 1,700 acres, authorities said.
Five homes were destroyed and 17 structures were damaged, Deputy Chief John Tripp of the Los Angeles County Fire Department said.
"We were able to save hundreds if not thousands of homes," Los Angeles County Fire Chief Daryl Osby said.
Glendora police Capt. Timothy Staab said three men were being held on $20,000 bail each. Clifford Henry, 22; Jonathan Jarrell, 23, and Steven Aguirre, 21 -- who described himself as homeless -- are accused of recklessly starting the fire. Staab said one of the men admitted they were tossing paper in a campfire when the wind kicked up. He did not say which one.
"One was very remorseful for starting this fire,'' Staab said.
