The order for the flight to the second blaze was canceled around the time of the crash, officials said Tuesday.
Preliminary witness reports suggested the aircraft had lost part of one engine or a wing after taking off from Reno-Stead Airport, said Ian Gregor, a spokesman for the Federal Aviation Administration.
The plane went down about a half-mile from the airport and burst into flame, Reno fire spokesman Steve Frady said.
The twin-engine P2V air tanker owned by Neptune Aviation of Missoula, Mont., had returned to the airport Monday after making one flight over a fire in California's Hope Valley south of Lake Tahoe during the morning, said Marnie Bonesteel, a spokeswoman with the Sierra Front Wildfire Cooperators.
The plane crashed after it took off to drop retardant on another fire in California later in the day, she said.
"They were fully fueled and did have a full load of retardant as well," Bonesteel said.
But with the cancellation of the mission to that second fire, a recall was issued for the plane, she said. It wasn't immediately clear if the crew had received the recall notice before the crash.
It was at least the third time a P2V owned by Neptune was involved in 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.
Neptune Aviation Chief Executive Officer Mark Timmons said he didn't have any additional information on the crash Tuesday.
Timmons said the P2V aircraft have proven to be extremely reliable, and the previous crashes were all attributed to pilot error.
He said the planes had undergone a special inspection that takes at least a month to conduct following fears in 1994 about using older aircraft. He also said continuing inspections, which include annual X-rays to look for cracks, are more intensive than those done on passenger planes.
Investigators for the FAA and National Transportation Safety Board were on their way to the scene, officials said.
The plane that crashed Monday was built in 1962 as an anti-submarine bomber for the Navy, officials said.
The fire in the Hope Valley had forced the evacuation of campgrounds, two mountain retreats and about 20 homes on Sunday. Evacuation orders were lifted Monday afternoon, and the fire, estimated at 200 acres, was 50 percent contained Tuesday.
Names of the victims had not been released.