MERLIN — A helicopter crash that killed nine people and left four injured in Northern California marked the second time tragedy has struck Grayback Forestry, a pioneer and leader in the business of wildland firefighting.

Grayback had 10 firefighters aboard the helicopter when it crashed shortly after takeoff Tuesday, said company spokeswoman Leslie Habetler.

It was ferrying them to a fire camp from a remote outpost fighting the Buckhorn fire on the Shasta-Trinity National Forest outside Redding, Calif.,

Seven Grayback firefighters are missing and presumed dead. Three were injured and are in hospitals. The Grayback crew was based in Medford, and the crew members are from Southern Oregon, Habetler said.

One of the Carson Helicopters Inc. pilots flying the Sikorsky 61N Fire King helicopter was killed, another was injured, and a U.S. Forest Service employee was also killed, Carson Helicopters said in a statement. The Forest Service has yet to confirm that it had a person aboard.

The Grayback firefighters were the first contract wildland firefighters killed in a helicopter crash, said Debbie Miley, executive director of the National Wildland Fire Suppression Association, which represents contract firefighting companies.

Six years ago, five Grayback firefighters from a crew based in La Grande were killed in a highway crash on their way to a fire in Colorado when the van driver lost control and the van rolled. The driver was cited for reckless driving.

Grayback was founded in 1979 by Mike Wheelock, a former smokejumper, and is one of the leading contract wildland firefighting companies in the nation.

Based in the small southwestern Oregon town Merlin, it employs about 500 firefighters, said company spokeswoman Leslie Habetler. The company has crews based in Medford, Canyon City and La Grande in Oregon and Missoula, Mont.

It provides 10 20-person crews dispatched around the country on wildfires.

For the wildland firefighters, transportation regularly accounts for the majority of fatalities each year, Miley said.

Private contractors account for 40 percent of the people fighting wildland fires nationwide, Miley added, mustering 10,000 to 12,000 people each year.

“Mike has been a real proponent in the industry of promotion of higher standards and also promoting the use of the best value contract system, which encourages quality versus quantity,” she said.

After the van wreck, Wheelock got rid of the vans that were the industry standard at the time for transporting firefighters and replaced them with trucks considered less prone to rollovers.

He also put his drivers through a special training course for handling big top-heavy rigs in critical situations.