The pilot of an air tanker fighting a wildfire near California's Yosemite National Park died Tuesday when the aircraft crashed.

California Fire spokeswoman Alyssa Smith said in a statement that crews reached the wreckage several hours after the crash and confirmed the pilot's death. The pilot's identity was not released because all immediate family had not yet been notified. 

"This crash underscores just how inherently dangerous wildland firefighting is and the job is  further compounded this year by extreme fire conditions," Chief Ken Pimlott, Cal Fire director, said in the statement. "We have secured the crash site and will be cooperating with the NTSB on their investigation."

Yosemite spokesman Scott Gediman told the Associated Press that the plane went down at approximately 4:30 p.m. local time less than a mile from the western entrance to the park. 

 California Highway Patrol Sgt. Chris Michael said he was stopping traffic along state Route 140 at the west entrance to the park about 4:24 p.m. when he witnessed the crash.

"I heard a large explosion, I looked up on the steep canyon wall and saw aircraft debris was actually raining down the side of the mountain after the impact," he told The Associated Press by telephone. "It hit the steep side of the canyon wall. It appeared from the direction he was going, he was trying to make a drop down the side of the canyon when he hit the canyon wall."

The fire was spreading up the canyon wall, and it appeared the pilot was trying to lay down fire retardant to stop its progress, Michael said.

"It most definitely did disintegrate on impact," he said. "It was nothing. I didn't see anything but small pieces."

Pieces of the aircraft landed on the highway and came close to hitting fire crews on the ground nearby, but no one on the ground was injured, he said.

"It came pretty close to hitting them, but they were far enough away that it missed them, fortunately," he said.

The airplane, manufactured in 2001, is an S-2T air tanker, which is flown by a single pilot and normally has no other crew members. The tanker uses twin turbine engines and is capable of carrying 1,200 gallons of fire retardant, said another CalFire spokesman, Daniel Berlant.

Don Talend, of West Dundee, Illinois, said he also may have seen the plane go down. Talend and friends were vacationing at the park when they stopped to snap some photographs of the fire, which was several miles away.

The plane "disappeared into the smoke and you heard a boom," he told The Associated Press by phone.

"I couldn't believe what I saw," Talend said. "There was actually a ranger there behind us. ... He had a look of disbelief on his face."

The pilot is an employee of DynCorp., a contractor that provides the pilots for all CalFire planes and maintenance for the department's aircraft, California department of Forestry and Fire Protection spokeswoman Janet Upton said.

The fire had broken out about 90 minutes earlier Tuesday near Route 140, which leads into the heart of the park. It had grown to about 130 acres by Tuesday evening and forced the evacuation of several dozen homes near the community of Foresta.

FAA records show the plane is registered to the U.S. Forest Service, which originally provided the plane to CalFire, Upton said.

The last time a CalFire air tanker crashed was in 2001, when two tankers collided while fighting a fire in Mendocino County, killing both pilots, Berlant said.

The agency had another plane crash in 2006, when a fire battalion chief and a pilot were killed while observing a fire in a two-seat plane in Tulare County.

The Associated Press contributed to this report.