Pine Flat, Calif. ? A raging wildfire threatened some of America’s giant sequoias Tuesday and the Forest Service called in more than 1,000 firefighters in an all-out effort to save the towering symbols of the West.

The 48,000-acre blaze roared through the deep valleys of the Giant Sequoia National Monument and came within two miles of the Trail of 100 Giants, a grove of majestic sequoias that are among the largest and most ancient trees on Earth, with trunks up to 1,500 years old and 20 feet in diameter.

As of noon, the fire had consumed only some smaller species of trees and the winds were blowing the flames away from the Trail of 100 Giants. But the blaze was headed toward another stand of the big redwoods, the Freeman Creek Grove.

Forest Service spokesman Matt Mathes called the sequoias “priceless” and said that air tankers and helicopters were also called in to help save the trees. The monument is situated 130 miles north of Los Angeles.

Sequoias can live more than 3,200 years, their massive trunks capable of withstanding countless fires. But fires can kill them when other trees spread flames to the sequoias’ limbs high above the ground.

The danger to the trees is higher than usual because of a considerable amount of underbrush and weeks of extremely dry weather, Mathes said.

“These trees can withstand a lot of fire, but if there’s a lot of fuel build-up on the forest floor, and temperature and humidity and winds are not favorable, we could have a problem,” he said.

Forest Service officials said the blaze was likely started by an escaped campfire Sunday, and it blew up as it fed on dry brush in a region that has not had rain since the spring. Smaller trees exploded like torches as the fire skipped from treetop to treetop, pushed by erratic winds. No arrests have been made.

More than 1,000 people fled and at least 10 structures were burned.

The fire was only 20 percent contained Tuesday.