By Steve Gorman
LOS ANGELES (Reuters) - A "human-caused" brush fire flared quickly out of control and prompted the evacuation of some 700 people on Tuesday from a mobile home park and nearby community in Southern California's Riverside County, state fire officials said.
The blaze erupted shortly before 12:30 p.m. local time (1730 GMT) and charred about 700 acres of drought-parched vegetation within five hours as flames roared through canyons and foothills in the Cherry Valley area, about 75 miles (120 km) east of Los Angeles.
No injuries were reported but the blaze destroyed one outbuilding, according to April Newman, a spokeswoman for the California Department of Forestry and Fire Protection (Cal Fire).
Sheriff's deputies immediately issued mandatory evacuation orders for the Highland Springs Village Mobile Home Park and dwellings in the nearby Banning Bench community to the northeast. Newman said an estimated 700 residents, from about 200 homes in all, were displaced.
Investigators determined the fire to be of unspecified human origin and asked for anyone with information about "juvenile activity" near the entrance to a park where the blaze began to contact an arson hotline, Cal Fire said on its website.
Authorities declined to give further information.
By late afternoon, winds were blowing the flames mostly away from populated areas "but we have them under evacuation because we have a ton of equipment coming in, and this is our access point to that fire," Cal Fire spokeswoman Liz Brown said.
More than 320 firefighters were initially assigned to the blaze, dubbed the Bogart Fire, and crews had managed to carve containment lines around 5 percent of its perimeter by 5.30 p.m. (2230 GMT), Cal Fire reported.
The firefighting force had grown to 410 personnel by then, backed by five helicopters and nine airplane tankers equipped to drop water and fire-retardant chemicals on the blaze.
Brown said temperatures that had reached into the low-triple-digits earlier in the day had subsided somewhat but humidity remained low and winds were relatively light, at 5 to 10 miles per hour (8-16 kmh).
Cal Fire reported about 12,000 firefighters battling about 10 other large fires across the state on Tuesday, most of which were largely contained or burning in remote areas. A total of 4,270 wildfires large and small have blackened more than 183,000 acres statewide so far this year, 30,000 acres more than at the same time last year.
(Reporting by Steve Gorman; Editing by Tom Brown and Paul Tait)