Firefighters in California's Sequoia National Park credited a controversial controlled burning policy with helping to save giant redwoods from a nearly 2,200-acre wildfire, and favorable weather helped crews near containment of a 4,100-acre blaze north of Los Angeles.

Under a policy pursued for about a decade in Sequoia National Park, rangers have been setting controlled fires or allowing lightning-set fires to burn unhindered to reduce the build-up of fallen trees, pine needles, leaves and other potential fuel.That tactic made it safe to set and carefully manage backfires when the blaze moved dangerously close to the Giant Forest, a famous grove of 200- to 300-foot-tall redwood trees up to 2,700 years old, said Larry Bankroft, acting park superintendent.

Meanwhile, a cooling trend with higher humidity and favorable winds moved over Southern California, helping firefighters Tuesday evening contain 90 percent of a brush fire that had burned 4,100 acres in the Angeles National Forest.

The blaze was touched off Sunday by a 10-year-old boy playing with matches at a campground surrounded by bone-dry chaparral in the forest above the San Fernando Valley community of Sylmar, 25 miles northwest of downtown Los Angeles.

U.S. Forest Service spokeswoman Kim Vanderhaar said the fire no longer threatened any structures. The turning point in efforts to contain the blaze was a major backfire operation Tuesday along the Kagel Canyon ridge, she said.

Firefighters torched close to 800 acres of dry brush in a controlled burn to remove fuel from the advancing fire.

Fire officials estimated the cost of fighting the blaze at $1.4 million. Full containment was expected sometime Wednesday with complete control anticipated Thursday.

Three firefighters suffered minor injuries, one of them a county jail inmate working on a fire crew who fell down a hill Monday and was hospitalized with hip and leg injuries.