CASTAIC (AP/CBS13) — Authorities have reopened nearly all lanes of a major Southern California highway as firefighters made progress on a wildfire.

The fire erupted Saturday in mountainous terrain near Castaic in northern Los Angeles County and grew to 450 acres, or more than half a square mile, prompting highway authorities to shut a stretch of Interstate 5 and crippling weekend traffic.

The roadway, commonly known as “The Grapevine,” is the main artery between Northern and Southern California.

The so-called “Route Fire” remains at zero percent containment Sunday morning.

Aircraft and ground crews plan to go directly at the fire and build containment, according to the Los Angeles County Fire Department.

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