A brush Fire near Murrieta has doubled in size to 700 acres and 200 homes were under mandatory evacuation orders in western Riverside County, officials said Friday morning.

Some residents were ordered to leave the community of La Cresta, just west of Wildomar, as ominous flames raged nearby. Others were under evacuations warnings, meaning they should be prepared to evacuate if necessary.

About a dozen horse trailers were seen moving out of the area, which is marked by ranch homes at the edge of the Cleveland National Forest.

The blaze was sparked by a motorcycle crash south of Lake Elsinore on Thursday afternoon, according to the California Highway Patrol.

It remained 15 percent contained after night-vision equipped helicopters performed water drops overnight and into the morning. Firefighters also set backfires in an effort to gain the upper hand.

There were no reports of injuries, and no structures have been damaged, a Cal Fire spokesman said.

Temperatures in Wildomar on Thursday are expected to reach a high of 94 degrees amid 46 percent humidity, according to the National Weather Service.

South Coast Air Quality Management District officials said weak offshore flow from the north will transition to onshore flow from the south and southwest, bringing smoke and ash into areas near the fire and potentially into nearby areas of Riverside County. They added that air quality may reach unhealthy levels or higher in areas Directly Impacted by smoke.

Areas that may be directly impacted by unhealthy air quality include portions of Lake Elsinore, Perris Valley and Temecula Valley. People are urged to avoid unnecessary outdoor activities where residents can see or smell smoke.