Henry Rodriguez, the public information officer for the Los Angeles County Fire Department, said the fire was 10% contained but had consumed 25,000 acres.
"This fire is the No. 1 priority in the state," Rodriguez said.
Twenty-five homes have been damaged and four people have been hurt, he said. About 800 people were evacuated Sunday.
"One of the challenges we're having with all the fires is getting [crews] coming in. We're doing the best we can with what we have," Rodriguez said.
FOR THE RECORD:
An earlier version of this article said 800 people had been evacuated. Eight hundred homes were evacuated.
He said the fire grew overnight because of the winds, which were 35 to 40 mph with gusts of up to 65 mph.
There were no new mandatory evacuations in effect, but officials said they were watching the situation. About 3,800 homes are threatened, according to Deputy Fire Chief Glenn Massey.
Karen Cayley, 55, a lifelong California resident, figured a wildfire might threaten her one day. She thought she knew the drill.
There would be some kind of warning, she thought. Even if she had to evacuate her home in Agua Dulce, between Santa Clarita and Palmdale, she would be able to collect a few essentials -- family photos, pets -- before leaving.
She had just started loading up Sunday and had her dog inside the car when a firefighter approached.
"Go now," he ordered her. "Don't take anything. Just go."
And she did -- so quickly that she had to leave everything else behind, including photos and two cats.
Of more than a dozen wind-swept firestorms that erupted across Southern California on Sunday, none, it appeared by nightfall, was more ferocious than the one dubbed the Buckweed fire.
The flames moved so rapidly that firefighters had to move their command center five times to keep ahead of them.
By 7 p.m. Sunday, the blaze had moved 10 miles west into Canyon Country, east of Santa Clarita. Smoke blanketed virtually the entire Santa Clarita Valley, and flames could be seen over numerous nearby ridges.
Paul Smith, 43, walked out of his house in the 19000 block of Newhouse Street in Canyon Country about 5 p.m. Sunday and saw flames on a nearby ridge.
"It started off with a small flame," he said. "Then it just started jumping and started smaller fires. Within five minutes, the whole ridge was on fire, and the flames were 100 feet tall."