CASTAIC (CBS/AP) — California highway authorities reopened nearly all lanes of Interstate 5 in Southern California Sunday as firefighters made progress on a wildfire that jumped across the road and spread across dry hillsides.

Dubbed the “Route Fire,” the blaze first broke out Saturday afternoon near Castaic in northern Los Angeles County. Pushed by 10-15 mph winds, flames chewed through tinder-dry brush and jumped across the busy freeway, spread across more than a half of a square mile.

Route Fire Burns Near Castaic

Traffic passes the Route fire, a brush wildfire off Interstate 5 north of Castaic, on Saturday, Sept. 11, 2021. (Los Angeles County Fire Air Operations via AP)

The California Highway Patrol closed a stretch of the interstate for several hours as air tankers dropped bright orange retardant on the flames.

Two firefighters were taken to the hospital to treat burn injuries, said Andrew Mitchell, a spokesman for the Angeles National Forest.

The fire remained uncontained due to the mountainous terrain but firefighters made progress overnight with the help of water-dropping aircraft and an aggressive ground attack, Mitchell said.

He said crews will take advantage of the beginning of a cooling trend Sunday to build containment lines.

The cause of the fire is under investigation.

© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report