Two lanes of northbound Interstate 5 reopened at about 8:30 tonight after a brush fire in northern Los Angeles County closed a northbound section of the freeway for most of Friday afternoon, the California Highway Patrol said.

The Associated Press reported that the fire in Castaic, which was reported just after 1 p.m., quickly grew to 650 acres.

County Fire Inspector Tony Imbrenda said the fire was in a remote, rugged area and no structures were threatened, according to the AP. Three hundred firefighters fought the flames.

The fire was 35 percent contained Friday evening.

Northbound traffic was heavily backed up around Valencia and Santa Clarita.

Because of the hilly terrain, much of the firefight was being handled by air with three helicopters making drops.

No injuries were reported.