The Lockheed P2V-7 had been dispatched Monday evening to fight a fire in California on the western slope of the Sierra Nevada.

But the tanker was no longer needed and was recalled around the time it went down at Reno-Stead airport, said Marnie Bonesteel, spokeswoman with the Sierra Front Wildfire Cooperators.

All three crew members were killed, bringing to 27 the number of deaths in fatal crashes of firefighting air tankers in the U.S since 1991.

The fire near West Point, Calif., in the Humboldt-Toiyabe National Forest was fully contained at 50 acres, according to the California Department of Forestry and Fire Protection's Web site.

Another air tanker sent to that fire was canceled while en route and returned to the airport in Minden, 50 miles south of Reno, Bonesteel said.

The plane, owned by Neptune Aviation of Missoula, Mont., was one of 12 the company had on contract with the U.S. Forest Service to fight fires.

It had made one flight over a different fire in California's Hope Valley south of Lake Tahoe on Monday morning and then returned to the Stead airport, where it remained until the fatal crash.

"They were fully fueled and did have a full load of retardant as well," Bonesteel said.

Investigators for the National Transportation Safety Board and Federal Aviation Administration were on the scene Tuesday at the small airport about 10 miles north of downtown Reno.

Witnesses reported seeing what appeared to be a piece of engine or wing fall from the aircraft before it caught fire and crashed about a half-mile from the runway, authorities said.

About 25 members of the Washoe County Sheriff Department were combing the runway and nearby areas Tuesday afternoon for any airplane parts or other clues to the cause of the crash, Deputy Darrin Rice said.

NTSB investigators were in the process of determining whether the witness accounts were credible, Rice said.

There were no immediate plans to ground any planes, said Christie Kalkowski, spokeswoman for the Humboldt-Toiyabe forest.

"Those planes under contract will continue to fly as requested and needed," she said Tuesday.

The P2V, originally developed by the Navy more than 50 years ago as a close-range bomber, has proven to be extremely reliable as an air tanker, said Neptune Aviation Chief Executive Officer Mark Timmons.

"I'm quite confident they are a safe platform," he said.

Each airplane has undergone an inspection that takes at least a month to conduct, following fears in 1994 about using older planes, Timmons said. He said ongoing inspections, which include annual X-rays to look for cracks, are more intensive than those done on passenger planes.

Monday's crash marked at least the third time a P2V owned by Neptune suffered a fatal crash while fighting wildfires on government contract over the past 15 years. Two men were killed when one crashed near Missoula in 1994, and two other men died in a crash near Reserve, N.M., in 1998.

Timmons said those previous crashes were found to be caused by pilot error.

"It is a dangerous business," he said. "We try to do as much as we can to decrease that amount of danger, but it is a dangerous business. There are risks in it."

The crash near Reno sparked a two-acre brush fire that was quickly extinguished. Sheriff's deputies cordoned off the site overnight.

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Associated Press writers Sandra Chereb and Martin Griffith in Reno and Matt Gouras in Helena, Mont., contributed to this report.