By Victoria Cavaliere
(Reuters) - Firefighters were making slow progress on Sunday in a battle to contain a wildfire that has roared through 1,600 acres of drought-stricken forest southeast of Los Angeles and displaced hundreds of people from their homes, the U.S. Forest Service said.
The Silverado Fire, which broke out Friday morning in the Cleveland National Forest, was 20 percent contained with 1,600 acres (647 hectares) charred as of Sunday, authorities said.
"Crews have gotten by the steepest, most rugged terrain," said U.S. Forest Service spokesman Jim Wilkins. "We are at 20 percent containment but that number should start going up rapidly now."
Three firefighters suffered minor injuries as more than 1,000 firefighters backed by nine helicopters were working around the clock to contain the blaze, which spread rapidly on Saturday as a heat wave gripped the state.
California is in its third year of a devastating drought, leaving bone-dry brush and chaparral that is feeding the wildfire.
"It has been well over 100 degrees here. It's very strenuous work," said Wilkins.
Evacuation orders remained in effect Sunday for 217 homes in and around Silverado Canyon, a gorge in the Santa Ana Mountains, officials said.
This year's wildfire season, which typically runs from May until October, was on track to be the most destructive on record, according to the California Department of Forestry and Fire Protection.
(Reporting by Victoria Cavaliere in Seattle; Editing by Cynthia Osterman)