Riverside firefighters have stopped forward progress of a wind-driven brush fire near the city's downtown that erupted around 11:15 a.m. on the perimeter of a Boy Scout camp near the Santa Ana River. It burned 50 acres.
Mandatory evacuations have started to be lifted. Evacuations remain in effect until 9 p.m. for east of Mission Inn Avenue, with the street itself closed until further notice, according to the department.
Between 300 and 400 homes were threatened as of midafternoon and at least two structures were slightly damaged, the Riverside Fire Department's Dave McClellan said, but no homes were lost. Local schools were keeping students inside due to poor air quality, the department said.
The fire department deployed units throughout neighborhoods due to spot fires that damaged a few of those homes, McClellan said. A woman trying to keep embers off the roof of her home fell and broke her leg, according to the department.
The cause of the fire remains under investigation. It started in the Santa Ana river bottom with heavy brush, with winds causing it to spread quickly, McClellan said. The fire was not near a homeless encampment.
Earlier Thursday, the the National Weather Service issued a red flag warning for Riverside County, where wind gusts have been reaching 40 mph.
This story has been updated.