The helicopter was carrying 11 firefighters and two crew members when it went down Tuesday night deep in the Shasta-Trinity National Forest and was destroyed by fire, according to the Federal Aviation Administration.
Four people - three firefighters and a pilot - were flown to hospitals with severe burns after other firefighters who were waiting to be picked up helped tend to their injuries, said Jennifer Rabuck, spokeswoman for the U.S. Forest Service. The rugged, dense terrain made it difficult for rescue crews to reach the crash site, Rabuck said.
The Forest Service and the Trinity County sheriff's department would not disclose Wednesday whether they had removed any bodies from the crash site or what the search effort entailed.
The National Transportation Safety Board said it had dispatched a team of investigators to survey the wreckage and to begin the long process of determining what caused the helicopter to crash.
Ten of the firefighters, including the three in the hospital, were employed by firefighting contractor Grayback Forestry, according to Kelli Matthews, a spokesman for the Merlin, Ore.-based company. Grayback's tally showed that seven of its employees were unaccounted for late Wednesday, and the company does not know whether any firefighters from other companies or government agencies also were on board, Matthews said.
She said the company was notifying families of the missing firefighters and fielding calls from anxious relatives asking whether their family members were among the injured or dead.
The firefighters had been working at the northern end of a fire burning on more than 27 square miles in the national forest, part of a larger complex of blazes that is mostly contained. Mike Wheelock, Grayback's founder and owner, said the company had two 20-person crews working the fire, a mix of young seasonal firefighters and professionals.
The accident was a painful reminder of how Grayback lost four firefighters in July 2002, when a van ferrying its workers from Oregon to a wildfire in Colorado's worst wildfire in history swerved off a highway and spun out of control, Wheelock said.
"We are just right now concentrating on all the families and our employees," Wheelock said while visiting the University of California, Davis Medical Center in Sacramento, where two of his employees were being treated. "We are very concerned about them because we are very tight-knit."
Grayback firefighters Michael Brown, 20, and Jonathan Frohreich, 18, as well as one of the two pilots, were being treated at the UC Davis hospital, according to the contractor. Brown was upgraded to fair condition late Wednesday and Frohreich remained in critical condition, according to the hospital and fire officials.
A spokesman said the hospital was also treating a victim in critical condition named William Coultas but could not confirm whether the patient was the co-pilot.
Leora Frohreich, Jonathan Frohreich's grandmother, said that it was the young man's first work as a wildland firefighter and that he planned to attend mechanic school this fall.
He had worked on a fire near Williams, Ore., for three weeks and then was on the Shasta-Trinity fire for four days, the grandmother said. His crew was being flown out for some rest when the helicopter crashed, she said.
"I'm so thankful because he's just lucky to be alive," Frohreich said, adding that the firefighter's parents, sister and girlfriend had gone to Sacramento to be with him. "You can't be in a crash like that and not hurt."
Another Grayback employee, identified as Richard Schroeder, 42, was in serious condition at Mercy Medical Center in Redding, officials said.
The helicopter was owned and operated by Carson Helicopters Inc., a Pennsylvania company whose firefighting operations are based in Grants Pass, Ore. All 12 of the company's helicopters are being used for firefighting in Oregon and California, said Bob Madden, Carson's director of corporate affairs.
The helicopter's two co-pilots were Carson employees, Madden said; one was hospitalized and the other was among the missing.
With the exception of the 2001 World Trade Center attack, which killed 340 firefighters, Tuesday's helicopter crash would rank as one of the deadliest incidents in the U.S. for firefighters in the past 30 years.
Before Tuesday's helicopter crash, three firefighters had been killed while on duty in California this year, including one firefighter also assigned to battle the Shasta-Trinity blazes who was killed last month by a falling tree.
On July 2, a volunteer firefighter in Mendocino County died of a heart attack on the fire line. Another firefighter was killed July 26 in when he was burned while scouting a fire.