The California Highway Patrol has shut a second freeway in the area.
CHP officer Patrick Kimball says a section of Interstate 5 near Sylmar was shut early Saturday as flames spread west toward the freeway.
About 5,000 residents have been evacuated since the fire started late Friday, and authorities say more evacuations are under way. Patients at one hospital were evacuated when the blaze knocked out power.
A separate fire in the Santa Barbara community of Montecito had forced evacuation of more than 5,400 homes since it started Thursday.