Orange County firefighters were battling a fast-moving brush fire in the Rancho Mission Viejo area Wednesday.
The blaze broke out just after 2 p.m. Wednesday near the 34700 block of Ortega Highway, Orange County Fire Authority Capt. Greg Barta said.
By 3 p.m. it had spread to about 150 acres, though no homes were threatened, officials said.
California Highway Patrol officers closed the highway eastbound at Gateway in Rancho Mission Viejo and westbound at Grand in Lake Elsinore, CHP Officer Brian Kinsey said.
Drivers were urged to avoid the area and take alternative routes such as routes 91, 76, 78 or Interstate 5.