The Record Fire was first observed burning in light to medium vegetation just after 2 p.m. in the area of Soboba Road and Gilman Springs Road, just north of San Jacinto.
It was initially estimated at about five acres but continued to spread, sending up thick plumes of smoke into the sky.
As of 8 p.m., containment was 0%.
The evacuation warning areas were described as: "RVC Poppet Flats 1, 2, 3 and 4. North of Wolf Road, West of Partridge Street and Hungry Hollow Road, South of Old Idyllwild Road and East of Gubner."
Authorities later described the fire as "human caused" and said it started at a homeless encampment. They are investigating whether that meant by arson or accident.
A map of the evacuation areas is posted here.
Six firefighters were brought to local hospitals to be treated for minor symptoms.