LOS ANGELES -- Authorities issued a mandatory evacuation order in east Anaheim Hills Monday in connection with an 1,800-acre brush fire in the Cleveland National Forest.

About 1,200 homes were under evacuation orders, with some mandatory and the others voluntary, but the breakdown between the two was not immediately available, said city spokesman John Nicoletti.

Those under mandatory evacuation live east of Serrano Road and south of Canyon Rim Road. Residents under voluntary evacuation order reside from Canyon Rim Road north to Oak Canyon Drive, all east of Serrano, Nicoletti said.

Residents who left their homes were directed to Villa Park High School and Travis Ranch Community Center in Yorba Linda, where the American Red Cross established shelters, Nicoletti said.

People who needed to relocate horses were told to take them to the south parking lot at Yorba Regional Park, he said.

"There are no reports of fire west of the 241 (Eastern Transportation Corridor)," Nicoletti said about 1:30 p.m. "None of the homes are being threatened. The reason is based on the potential of winds kicking up."

Students at three schools were relocated because of smoke from the fast-moving brush blaze, which broke out on a day when weather forecasters issued a Red Flag Alert due to high fire danger. Students from Canyon Rim Elementary, Santiago Charter Middle School and Anaheim Hills Elementary were sent to Canyon Hills High School, a school spokeswoman said.

Firefighters were battling to ensure that the flames did not jump west of the (241), which they hoped would continue to act as a barrier to protect homes in Anaheim Hills and Orange Hills, said Orange County Fire Authority Capt. Stephen Miller.

Flying embers started two small spot fires across the highway, about a half-mile from the closest homes, which sparked the evacuation order, Miller said.

The blaze broke out before dawn in a mountainous area between Orange and Riverside counties near Sierra Peak, Miller said.

Miller said he did not know if there were power lines in the area, which is remote. He had no information as to how the fire started.

Firefighters carried out an aerial assault on the blaze using water-dropping helicopters, working from a command post established at Irvine Regional Park. There was no immediate word on containment, Miller said, adding that "once we get a helicopter freed we'll map" the fire.

As a precaution, officials closed the 241 toll road between Santiago Canyon Road and the Riverside (91) Freeway, said California Highway Patrol Officer Denise Quesada.

Fighting the blaze along with personnel from the OCFA were federal and state firefighters. Because of a Red Flag Warning in the Southland, many firefighters were pre-deployed in various areas. About 500 firefighters were at the scene Monday evening, officials said.

The 460,000-acre Cleveland National Forest is the southernmost national forest in the state.

Health Warning

The County of Orange Health Care Agency warned late this morning that smoke from the wildfires posed a public health danger.

"Among those who can be most directly affected by smoke exposure are individuals with heart and respiratory diseases, older adults, children and pregnant women," said Acting County Health Officer Hildy Meyers.

People in areas downwind from the smoke were urged to limit outdoor activity and physical exertion until the smoke diminishes; keep windows and doors closed; and use air conditioning.

People should call a doctor if experiencing symptoms of chest pain, chest tightness, shortness of breath or severe fatigue, according to Meyers.

Red Flag Warning

The strong winds whipping across the Southland Monday come with unusually high temperatures and low humidity, and that has prompted a National Weather Service Red Flag Warning, signifying a high risk of wildfire.

Severe Weather Alerts

The warning went into effect at 6 a.m. Monday and was scheduled to expire at 6 p.m. in the valleys of Los Angeles County and at 6 p.m. Wednesday in mountain areas.

National Weather Service meteorologists are forecasting winds of between 20 and 30 mph, gusting up to more than 40 mph, in the San Fernando, San Gabriel and Santa Clarita valleys and even higher in the mountains.

Temperatures will climb to near-record levels and may set record highs in some areas, according to forecasters. Standing records for Feb. 6 include 86 in downtown Los Angeles and Burbank and 87 in Pasadena, according to the NWS.