BISMARCK, N.D. (AP) — Federal investigators say they found no evidence of a mechanical failure before a North Dakota state senator’s plane crashed in Utah last month, killing him, his wife and their two young children, according to a preliminary report released Thursday by the National Transportation Safety Board.

Doug and Amy Larsen and their two sons, 11-year-old Christian and 8-year-old Everett, died Oct. 1 in the crash near Moab, Utah. The family’s single-engine aircraft went down shortly after they stopped to refuel while returning home from a family gathering in Arizona.

The plane was piloted by Doug Larsen, 47, who flew Black Hawk helicopters and mobilized twice during his 29 years with the North Dakota Army National Guard.

Security video at the airport showed Larson buying 27 gallons (102 liters) of fuel at a self-serve island at the airport shortly after landing around 5:45 p.m. before borrowing a car to drive into town, the NTSB said.

The group returned to the airport shortly after 8 p.m. and got back into the plane. The video showed the plane’s lights illuminate before it rolled down the runway and took off at 8:23 p.m. The report noted that the runway lights, which are controlled by the pilot, remained dark during takeoff.

The plane climbed to about 200 feet (61 meters) and turned around after takeoff, but started to descend shortly thereafter and crashed within minutes. A witness reported hearing two distinct impacts when the plane crashed. Investigators found that the plane gouged a hilltop before crashing about 455 feet (139 8 meters) away.

The NTSB said its examination of the wreckage “revealed no mechanical malfunctions or failures that would have precluded normal operations.”

Larsen had recently earned his commercial pilot’s license and had hopes of one day flying for a major airline, state Sen. Jim Roers said.

He was awarded the Meritorious Service Medal, Bronze Service Star and Army Aviator Badge, among other honors. He had logged about 1,800 total military flight hours, according to National Guard spokesperson Nathan Rivard.

Larsen was posthumously promoted from lieutenant colonel to colonel, having met the criteria for promotion, Rivard said.

Dozens of state lawmakers attended the funerals that were held Oct. 10 for the Larsens. They were laid to rest in the North Dakota Veterans Cemetery.

Larsen, a Republican, was elected to the North Dakota Senate in 2020. In the 2023 session, he chaired a Senate panel that handled industry- and business-related legislation.

District Republicans recently appointed a successor for his seat representing Mandan, the city neighboring Bismarck to the west across the Missouri River. Justin Gerhardt, a project manager with a construction company who served nine years with the North Dakota Army National Guard, will serve the remainder of Larsen’s term through November 2024. The seat is on the ballot next year for a full, four-year term.

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Associated Press writer Josh Funk contributed to this report from Omaha, Nebraska.