ESTES PARK, Colo. (KDVR) — Federal aviation investigators on Wednesday released a preliminary report on the fatal air tanker crash near the Kruger Rock Fire.

On Nov. 16, pilot March Thor Olson flew the tanker from Fort Collins to fight the fire, which sparked amid high winds and low humidity. The single-engine aircraft, an Air Tractor 802A, crashed around 6:30 p.m. on its second firefighting run.

In the report, the National Transportation Safety Board shared witness accounts from the moments prior to the plane crash.

“Video of the airplane showed the airplane wings rocking as it approached the intended drop location for the aerial firefighting of the Kruger Rock fire,” the NTSB wrote in the report. “Two witnesses stated that they saw the airplane roll inverted and did not see it descend into terrain. One of the witnesses, who was in radio communication with the pilot, stated that he did not hear the pilot transmit any problems with the airplane nor make any distress calls prior to the accident.”

Investigators found the wreckage “was upright and displayed features of a low-speed, nose-down impact with slowing and wooded terrain” and with no ground scarring ahead of it.

The NTSB said it retained the wreckage “for further examination.”

CO Fire Aviation owned the plane. The company has aircraft outfitted with night-vision technology to help see through smoke and clouds during firefights — a tool new to Colorado.

Larimer County has said it asked the company for help attacking the fire that night, as ground conditions were too dangerous for crews. After one successful run, the pilot returned for a second and reportedly said conditions were not ideal for a second drop, according to the county.

Moments later, he crashed.

The NTSB will issue a final report at a later date.