A brush fire that burned 50 acres just off the Ronald Reagan Freeway in Simi Valley early Monday forced the highway's closure in both directions before firefighters got it under control.
Firefighters had the fire fully contained by 8 a.m., said Sandi Wells, a spokeswoman for the Ventura County Fire Department.
Fire investigators are trying to determine the cause of the blaze, which broke out about 1 a.m. in a field west of Erringer Road and north of the freeway.
No homes or other structures were threatened, Wells said. Smoke was visible from a mile away as it engulfed several eucalyptus trees and acres of dried brush. Gusting winds swept embers to a center divider on the freeway, where they ignited a grassy area.
Jaye Neville, a dispatcher with the California Highway Patrol, said the roadway was shut down from about 2:30 to 4 a.m.
Thirteen engines and 146 firefighters from Ventura and Los Angeles counties and the California Department of Forestry battled the fire, Wells said.