A pilot was killed and two state troopers were injured after a state police helicopter collided with a small plane during a training exercise at a central Pennsylvania airport Wednesday evening, officials said.

The collision occurred around 6:52 p.m. at Carlisle Regional Airport in Cumberland County, around 120 miles west of Philadelphia, police said.

The two-man helicopter crew was conducting routine training exercises on a grassy area adjacent to a runway when a small, two-seater Cessna Model 150 plane struck the helicopter from the rear after going down the runway and veering to the right, State Police Acting Commissioner Lieutenant Colonel George Bivens said at a press conference.

The helicopter was “several feet off the ground” at the time of the collision, Bivens said. “The pilots would not have been able to even see that airplane approaching them,” Bivens said, describing the collision as “a very violent crash.”

Bivens said the two pilots were initially trapped inside the helicopter. One trooper was able to push out a window and assist the other trooper to free themselves before emergency responders arrived at the scene, he said.

The Federal Aviation Administration and the National Transportation Safety Board are investigating the crash with assistance from the Pennsylvania State Police, Bivens said.

Only the pilot, who authorities have not identified, was believed to be on board the Cessna, but Bivens said that remains part of the investigation.

Pennsylvania Gov. Josh Shapiro identified the two state troopers as State Police Corporal Pilot Bryce Corman and Trooper Pilot Jason Mills.

“Tonight could have been much worse. Tonight could have been much more tragic for our state police family. Thank god that it wasn’t,” Shapiro said, adding he has been in touch with their families.

Wreckage of the helicopter with the state police emblem was seen laying on its side near the airport’s runway in video from CNN affiliate WPMT.

There has been increased attention to airspace shared between helicopters and planes since last year’s midair collision at Ronald Reagan Washington National Airport killed 67 people. In that crash, a US Army Blackhawk helicopter collided with an American Airlines regional jet as it was landing.

Carlisle Airport has a single 4,000-foot-long runway. There is no control tower at the field, so pilots communicate their intentions on a common radio frequency, an arrangement common at small airports. (CNN)