A FedEx truck caught fire Wednesday on the 5 Freeway in Castaic, prompting the closure of two southbound lanes for several hours, authorities said.
Firefighters were seen battling the blaze that engulfed the front of the truck and spread to a nearby hill, just north of Lake Hughes Road.
The brush fire was confined to less than 1 acre as of 4:15 p.m., according to the Los Angeles County Fire Department.
Aerial video from Sky5 showed traffic backed up for miles as firefighters worked to extinguish the fire.
Caltrans said the backup stretched about 3.7 miles long.
A SigAlert was issued for the southbound lanes, which were expected to stay closed for at least two hours, according to California Highway Patrol.
The two lanes were expected to reopen at 9 p.m., Caltrans said in a tweet.
Authorities did not provide information on what started the fire or if anyone was injured.
No further details were immediately available.