The cause of the fire that started Sunday afternoon in the San Gabriel Mountains, spoiling holiday hiking and camping plans for thousands, has not been determined, the California Department of Forestry and Fire Protection said.
A burned car was found in the area, but it isn't clear if it started the fire or was just destroyed by the flames, officials said.
No structures have burned. Five minor firefighter injuries have been reported, four for heat and one twisted ankle, said Calfire Incident Cmdr. James Smith. No one has been hospitalized.
Fire conditions early Tuesday were good, with temperatures in the upper 60s, 6-mph winds and humidity at 20 percent, Smith said.
Resources on the fire include four air tankers, 10 helicopters, 40 engines, eight dozers, 25 hand crews and five water tenders, he said.Campgrounds that typically attract up to 12,000 visitors on the holiday weekend, as well as rehabilitation centers and a private mobile home community of Camp Williams Resort, were evacuated Sunday but some stuck around.
"Twenty-five people have elected to stay in place regardless of the evacuation order," Smith said.
Daniel Burress, 68, known to park residents as "Grandpa," said he has never evacuated, even when wildfires were far closer.
"I'm a Vietnam vet," Burress told the Los Angeles Times. "So this doesn't scare me at all."
Officials said campgrounds, while not in the line of the fire, had to be emptied so the only road in and out of the San Gabriel Canyon could be open just for fire trucks and emergency vehicles.
The area burned is about 5 1/2 square miles. The latest update Tuesday estimated the fire to be 15 percent contained, Smith said.
The reason it will take so long to circle the fire is because the basic firefight is taking place from the air, Capt. Roland Spreewell told KTTV-TV. "It's hard to get boots on the ground" because of the "billy goat" conditions, he said, explaining that much of the fire area had slopes of 30 percent to 80 percent.
In Northern California, firefighters spent Monday focusing on the rugged and remote northern edge of a weeks-old fire in Mendocino County. That blaze has scorched more than 65 square miles.
At least two other fires were contained Monday shortly after they started: a 150-acre brush fire in hills between Concord and Pittsburg on Northern California and a 100-acre blaze in Fountain Springs near Porterville in Southern California.