The so-called Tumbleweed Fire was reported shortly before 2 p.m. near Gorman Post Road and the southbound side of the freeway, according to the Los Angeles County Sheriff's Department. Authorities said flames were being driven by winds in the area - which, according to the National Weather Service, are gusting between 18 and 25 mph.
The blaze was initially reported at 200 acres, but quickly grew in size. It is 10% contained.
No structural damage was immediately reported, but two firefighters suffered minor injuries, authorities said.
Evacuations were under way for the Gorman Park Area in Gorman, the Sheriff's Department said.
The cause of the fire was unknown.