A DC-10 tanker drops flame retardant in the Guiberson Fire burn area.
A fire in the Moorpark area grew by just a few hundred acres overnight as firefighters continued to battle the blaze from the ground and in the air.
Heat and very low humidity are keeping fire danger high Thursday, although the National Weather Service says the dry Santa Ana winds that spread the flames through rural Ventura County are weakening.
More than 20 helicopters are working the fire along with air tankers, bulldozers and 1,800 firefighters. Helicopters are dropping water as bulldozers carve firebreaks to stop the 25-square-mile wildfire, which is 40 percent contained.
Authorities said they plan to reopen Highway 23 Thursday.
"The majority of the activity is going to be on that northeast corner, moving toward the town of Piru," said Capt. Ron Oatman.
Oatman said full containment is possible by Saturday.
The wind-driven wildfire in Ventura County grew to 16,400 acres Thursday. The Guiberson Fire started Tuesday at about 10:30 a.m. The fast-moving blaze originated near the 126 Freeway, just east of Fillmore.
The fire was believed to have been ignited by spontaneous combustion of manure at a ranch, according to a Sheriff's Department statement.
All road closures, evacuation areas, and shelter information are being updated online:
The Los Angeles Times has posted this Google map:
View Ventura County fire map 9/22/09 in a larger map