CASTAIC, Calif. (KABC) -- As a brutal heat wave enveloped Southern California, a brush fire near Castaic scorched more than 4,600 acres in a matter of hours, forcing evacuations and the closure of the 5 Freeway.
The Route Fire started around noon near the 5 Freeway at Lake Hughes Road. With triple-digit temperatures and thousands of acres of dry brush on the ground, it spread quickly.
More than 360 firefighters and 15 aircraft from multiple local and federal agencies were deployed to battle the blaze, protect structures and assist with evacuations.
With every update from fire officials, the blaze seemed to grow exponentially. It was first estimated at seven acres, but the numbers kept going up - first 20 acres, then 60, then 130 just an hour after it started. By around 7 p.m. the fire had exploded in size to 4,600 acres.
The flames were sending thick plumes of smoke thousands of feet into the air, combining with atmospheric conditions to form anvil-shaped clouds. The smoke was reported to be visible from Orange County.
At an evening press conference, firefighters said they were expecting to keep the battle going through the night and into the next day. But they also needed to keep resources spread throughout the region with the likelihood of more fires elsewhere during a Southern California heat wave that is forecast to last into next week.
The heat was taking its toll on firefighters, who had to wear heavy gear and carry equipment during temperatures that were already above 100 degrees regardless of the fire.
Eight of them were treated for heat-releated injuries - six of those had to be transported to local hospitals. They were all expected to recover.
"The folks out there are just taking a beating," said Deputy Chief Tom Ewald, with Los Angeles County fire. "We're advocating for them to hydrate, for supervisors to pay attention to their condition."
The fire caused the shutdown of the 5 Freeway in both directions by 1 p.m., leaving thousands of drivers stuck on the road in the heat with nowhere to go as officials worked to gradually divert traffic onto surface streets.
At an evening press conference, CHP officials said they were working to get the freeway reopened, but had to inspect the roadway and guardrail to make sure it was structurally safe. There was no estimate on when it might reopen but at 7:30 p.m. a CHP captain said it could be "relatively soon."
Evacuations were ordered for Paradise Mobile Estates and all structures south of Templin Highway along Upper Ridge Route Road. Residents in that area were ordered to evacuate to the north, according to the Los Angeles County Sheriff's Department.
Northlake Elementary was also being evacuated by sheriff's deputies.
About 100 to 200 homes were evacuated in the area.
A Red Cross evacuation center was expected to open by 9 p.m. at West Ranch High School, at 26255 Valencia Blvd. in Santa Clarita.
Los Angeles County has set up a website to provide emergency updates about the fire.
The excessive heat warning for the Castaic Lake area was not scheduled to expire until 8 p.m. Monday.
The cause of the blaze was unknown.
The prolonged heat wave began pushing up temperatures earlier this week, marking the onset of an expected weeklong period of oppressively hot conditions. The forecast has prompted calls for residents to take precautions against heatstroke and to conserve power whenever possible, with state officials warning of possible strain on California's electrical grid.
"High pressure will persist over the area creating a prolonged period of very hot conditions with minimal coastal clouds,'' the National Weather Service said. "Triple-digit heat is expected for many valley and mountain locations through early next week including coastal areas during the Sunday and Labor Day peak. This heat may be record breaking and will produce a very high risk of heat illness.''