The blaze near state Route 76 and Old Highway 395 erupted for unknown reasons about 1 p.m., Cal Fire reported. As of about 10:30 p.m., the blaze was 5 percent contained.
Interstate 15, Old Highway 395 and state Route 76 were all closed near the blaze for several hours, but have since been reopened.
County officials said almost 600 households were contacted via the reverse 911 system, which urged residents to evacuate to Fallbrook High School, 2400 S. Stage Coach Lane. Cal Fire officials said the evacuation order was lifted Wednesday night.