"The fire is pretty much out, but the mop up is usually the hardest part," said Inspector Fredrick Stowers of L.A. county fire. "We need to go back over and make sure we comb this fire. It's about 12 acres and we want to make sure we get all the hot spots and that there are no embers left so the fire doesn't restart again."
Crews working on a hillside along the 101 Freeway were looking to neutralize hot spots to make sure the fire didn't come back to life.
Authorities were investigating the cause of the fire.
No structures were immediately threatened, although the fire burned near homes and office complexes.
The Los Angeles County Fire Department launched a quick attack from the air and ground.
A large plume of smoke was visible from the San Fernando Valley.
Authorities closed Mureau Road between Mountain View Drive and its overpass above the 101 at Calabasas Road around 1 p.m. Also, two lanes of the westbound 101 were blocked by fire trucks.
No evacuations or road closures were ordered by deputies, but half of the four westbound lanes were closed by 12:30 p.m. and remained closed nearly three hours later.
Traffic was creeping west at 5 miles per hour, according to Caltrans data, and cars could be seen for miles even though the flames were out.
CNS contributed to this report.