Six structures burned and a road closure was in place after a 500-acre wildfire broke out in the Castaic Canyons area Sunday afternoon, according to officials.
The fire grew to 500 acres and no containment was reached as of Sunday night, according to InciWeb, a website that monitors fires.
Three structures that were part of the Warm Springs Rehabilitation Center, which was vacant and not in use, burned and were determined to be a loss, Santa Clarita Valley Sheriff's Department Sgt. Brian Allen said.
Three additional structures, none of which were homes, later caught fire, Los Angeles County Fire Department Supervisor Ornelas said.
The fire also prompted a closure of Lake Hughes Road at Elizabeth Lake, the California Highway Patrol tweeted around 6:08 p.m.
Additional structures were not believed to be threatened and evacuations were not planned, but on-scene officials feared the fire had the potential to burn up to 2,000 acres.
Firefighters faced dry terrain and soaring, triple-digit temperatures Sunday, according to the National Weather Service. Temperatures were expected to stay in the high 90s Monday.
The Warm Fire was considered a wildfire, according to the U.S. Forest Service, and burned near the border of unincorporated Castaic Canyons and Ridge Route.
The blaze was one of three in Los Angeles County on Sunday, including the Lincoln Fire in the Montebello area which broke out hours prior, and the 1,448-acre Cabin Fire burning in the Angeles National Forest above Glendora.
The fires burned as an excessive heat warning was issued by the National Weather Service. It was set to expire at 8 p.m.