Nearly 2,000 residents were evacuated and two homes burned in a wildfire that started when three people lit a campfire in the dry foothills of Southern California's San Gabriel Mountains, authorities said.
Embers from the fire fanned by Santa Ana winds quickly spread into an area below where residents were awakened in the pre-dawn darkness and ordered to evacuate.
The three suspects, all men in their 20s, were arrested on charges of recklessly starting the fire that spread smoke across the Los Angeles basin.
One resident suffered minor burns in the area abutting Angeles National Forest, just north of the San Gabriel Valley community of Glendora, according to Los Angeles County Fire Chief Daryl L Osby.
Between 1,700 and 2,000 residents were evacuated and the order included 880 homes in Glendora and the neighbouring foothill city of Azusa. Many residents, some wearing masks, used garden hoses to wet the brush around their houses, even as firefighters ordered them to leave.
At least two and a half square miles of dry brush were charred in the wilderness area about 25 miles northeast of downtown Los Angeles.
Police said the three suspects were detained near Colby Trail, where the fire was believed to have started. At least one was homeless, Glendora Police Chief Tim Staab said.
Glendora police said officers went door to door ordering residents of the city of 50,000 to leave. Citrus College, located in the heart of Glendora, cancelled classes for the day and s everal schools were closed.
More than 700 firefighters were on the scene. The Los Angeles County Fire Department deployed seven engines and three helicopters to the pre-dawn fire. Officials added to the firefighting aircraft with a water-dropping Super Scooper plane.