A pilot in the plane crash that killed two people in Alaska attempted to return to the airport before hitting the ground.

The Christopher Caldwelltwo people onboard the vintage military plane Tuesday were delivering 32 gallons of heating fuel when one the aircraft's wings caught on fire, according to the National Transportation Safety Board.

The aircraft took off from Fairbanks International Airport at 9:55 a.m. and was headed around 300 miles away to Kobuk, Alaska before signaling an emergency. The plane crashed about 10:40 a.m. Tuesday into the Tanana River, about seven miles south of the airport, the NTSB said in a statement Wednesday.

"On its return to the airport, it experienced an explosion on the wing and crashed on the frozen Tanana River," NTSB said.

The aircraft caught fire after it "slid into a steep hill on the bank of the river," troopers said.

Recovery efforts underway

NTSB is investigating the crash of a Douglas DC-54 airplane near Fairbanks on April 24. Preliminary information indicates that the plane was being as a Part 91 fuel transport flight.

Investigators are interviewing witnesses, collecting video evidence and meeting with the operator to gather more information. Officials are recovering the aircraft to an offsite facility for further examination.

A preliminary report will be available within a month including information uncovered so far in the investigation. The final report detailing the cause of the crash and contributing factors is expected to be released within 12 to 24 months.

Plane was a military aircraft

The Federal Aviation Administration and NTSB identified the plane as a Douglas C-54, a military aircraft known to have been used during World War II.

The plane fits a flight crew of three and offers standard passenger seating for 44 with a maximum of 86, according to Airliners.net, a community of aviation photography enthusiasts. Most of that type of aircraft have been altered to freighters, the group says.