LOS ANGELES — The fire moved fast, faster than even veteran firefighters had seen. As it ripped down a hill toward Middletown, two hours north of San Francisco, some residents hardly had time to dress before they fled.

“We were surrounded by fire,” said Maddie Ross, 25, a student at Santa Rosa Junior College who fled with her grandparents on Saturday from their home in nearby Hidden Valley Lake.

They did not even have time to put their shoes on. “It looked like hell everywhere,” Ms. Ross said. “It was terrifying, truly terrifying. I’ve never been in a situation like that. We all felt like the world was coming to an end.”

By Sunday afternoon, up to 1,000 homes and commercial structures had been burned by the so-called Valley fire. They were the latest casualties of the worst drought in California’s recorded history, which has left hillsides thick with dry brush and made wildfires more common than ever.