RENO, Nev. - Federal investigators said they're perplexed by the jet engine fire that preceded the fatal crash of an air tanker near Reno this week because there's been no known similar incident before with that type of aircraft.

They also said the Lockheed P2V-7 that crashed shortly after take off Monday evening from Reno-Stead Airport had been inspected not long ago and was only about 36 hours through a normal 100-hour inspection schedule.

"The cause of the fire, that is the question. And that might not be forthcoming for some time," Tom Little, lead investigator for the National Transportation Safety Board, said at a briefing Wednesday night.

"I asked the operator if they had ever experienced anything like this and they haven't," he said.

The plane owned by Neptune Aviation Services of Missoula, Mont., and built in 1962 was one of 12 the company had on contract with the Forest Service to fight fires.

At least two witnesses saw one of the plane's two jet engines on fire shortly after take off. The flames engulfed the left wing before the plane went into a roll and crashed, killing all three members of the aerial firefighting crew, he said.

The Washoe County Coroner's Office identified the three victims on Wednesday as Calvin Gene Wahlstrom, 61, of Hunstville, Utah; Gregory Gonsioroski, 41, of Baker, Mont.; and Zachary Jake Vander-Griend, 25, of Missoula, Mont.

Gonsioroski's sister-in-law Kristi Freeman said the family was making funeral arrangements for today in Baker, a small eastern Montana town near the North Dakota border.

"He loved to fly, and I think he just enjoyed doing something that allowed him to help others," Freeman said.

A cousin of Wahlstrom, Teri Busick of Huntsville, said the pilot's wife and brother were flown to the crash site Tuesday.

"It's a brutally dangerous job, probably the most dangerous job in our country," Busick told the Standard-Examiner of Ogden, Utah. "There are so few of them and so many deaths."

A total of 27 crew members have been killed in crashes involving firefighting air tankers since 1991.

Little told reporters on Tuesday that investigators had recovered several large pieces of metal beginning about one-quarter mile north of the runway that appear to have come from the burning engine.