Mandatory evacuations were ordered for residents north of Sage Road, south of Stanley Road, east of Benton Road and west of Reed Valley Road.
An evacuation center has been opened by the American Red Cross at the Community Recreation Center, located at 30875 Rancho Vista Road in Temecula.
The brush fire, dubbed the "Buck Fire," had burned about 1,800 acres by 6:05 p.m., with 5-percent containment. Three structures were damaged and nine homes had been evacuated. One house was a total loss.
The flames began in the area of Sage Road between Lewis Valley and Buck roads. The fire was reported about 1 p.m.
Six air-tankers and six water-dropping helicopters were assisting Cal-Fire ground crews battling the blaze. Four bulldozers were also on scene. About 210 firefighting personnel were part of the effort. Orange County Fire Authority and Riverside County Fire Department firefighters were assisting.
No injuries were reported.
Aguanga is a community located about 18 miles east of Temecula, 25 miles southeast of Murrieta and about 30 miles northeast of Fallbrook.
The cause of the fire was under investigation.
Power company Anza Electric Cooperative Inc. said that power will remain off in the Red Mountain, Benton and Stanley road areas until further notice due to the vegetation fire; the Reed Valley area may also be affected.
Helton Hay and Feed offered shelter for horses in the area if evacuated. Helton Hay and Feed is located at 26852 Bradley Road in Menifee, and can be reached at (951) 775-2226.
The Big Red Barn Petting Zoo in Winchester announced the facility can take evacuated animals. The establishment is located at 32720 Keller Road in Winchester, and can be reached at (951) 926-0850.
KABC-TV Los Angeles, CA contributed to this report.