CARLISLE, Pa. (AP) — Investigators are working to understand why a small plane veered to the side while landing at a rural airport and crashed into a hovering Pennsylvania State Police helicopter, a federal official said Thursday.

Aaron McCarter, investigator-in-charge with the National Transportation Safety Board, said there is not an immediate explanation for Wednesday's fatal collision that killed the pilot of the small aircraft and injured two state troopers.

“Many of you have all seen the videos that have turned up online. It’s very dramatic. That shows the collision. We see the outcome, but we want to understand why it happened,” McCarter said.

He said the wreckage from the crash will be analyzed and they will examine the aircraft, the actions of the pilots and the environment at the time of the crash.

The crash at the small airport in Carlisle, about 110 miles (170 kilometers) northwest of Philadelphia, involved the Bell 407 helicopter and the Cessna 150, according to the Federal Aviation Administration.

The Cessna 150 was attempting to land when it veered to the side and collided midair with the rear of the police helicopter, which was hovering above a grassy area beside the runway as part of a training exercise, according to the Pennsylvania State Police.

The small plane struck the tail of the hovering helicopter, killing the Cessna pilot and sending both aircraft to the ground in pieces.

McCarter said both pilots were flight instructors. There was not a tower to control traffic at the airport, but pilots communicate on a common frequency. He said communication was established between the flight crews, and they have strong evidence that the Cessna pilot was made aware of the helicopter hovering in the area.

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“I can’t tell you whether or not his visual acuity or whether or not the helicopter was blocked from view,” McCarter said.

McCarter said the Cessna pilot had been doing maintenance on his plane before the flight, but they don’t know yet if there was a mechanical issue. He said the flight path of the plane was unusual, and they are looking at why the plane came in that direction and suddenly turned.

“I have no information at all to tell me either pilot of either vehicle was at fault. We are very early in the investigation to determine that,” McCarter said.

The pilot of the plane was identified as Paul William Sokoloski, 57, according to the Cumberland County Coroner’s Office.

The helicopter lost its blades and tail boom and crashed onto its side. Both pilots in the helicopter were trapped until one pushed out a window and helped the other out through it, Lt. Col. George Bivens, the state’s acting police commissioner, said during a Wednesday night news conference.

“When I say it was a very violent crash, that plane was cut into a lot of pieces,” Bivens said.

The helicopter was piloted by Cpl. Bryce Corman and Trooper Jason Mills. Both were airlifted to Penn State Health Milton S. Hershey Medical Center for treatment. Corman has been released from the hospital and Mills is recovering in the hospital with a good prognosis, Gov. Josh Shapiro said Thursday.

The pilot was the only person aboard the Cessna.