They will be looking into what caused a small plane and a state police helicopter to collide midair in Central Pennsylvania Wednesday night.
The Federal Aviation Administration and National Transportation Safety Board are both investigating.
Here's what we know so far.
The crash happened at the Carlisle Airport in Cumberland County, southwest of Harrisburg, around 7 p.m.
When first responders arrived at the scene, a Pennsylvania state police helicopter was on its side and a small plane was in pieces.
The acting commissioner of the state police said the helicopter crew, based out of Harrisburg, had been conducting routine training exercises.
"The pilots would not have been able to even see that airplane approaching them," said Pennsylvania State Police Acting Commissioner Col. George Bivens, adding that it was a "very violent crash."
A witness nearby said he was mowing his lawn when he heard the crash.
"Probably five seconds after I turned my back, I heard a huge crash," Lloyd Slusser told Action News. "Immediately grabbed the phone. My neighbor was out and she said she called 911."
At 6:52 p.m., state police said the helicopter was hovering several feet off the ground over a grassy area, adjacent to a runway, when a small Cessna model 150 that was lined up to land on a runway veered right at the last moment, striking the helicopter in the rear.
"The helicopter, without its blades and without its tail boom, rolled inverted and crashed into the ground on its side, and partially onto its roof," Bivens said. "Both pilots from inside the helicopter were trapped inside the helicopter."
The Cessna crashed a short distance away and broke into multiple pieces.
The pilot, who was the sole occupant of the plane, did not survive. Authorities did not immediately identify the pilot, pending notification of next of kin.
Corporal Bryce Corman and Trooper Jason Mills were both trapped, but Bivens said the corporal pushed out a window and assisted the trooper out.
Both men got out amid concerns the damaged aircraft could catch fire.
Dr. Ashley Ludwig, trauma medical director at Hershey Medical Center, said both troopers arrived as Level 1 trauma patients but suffered only minor injuries and were in stable condition. One was expected to possibly be discharged Wednesday night, while the other was being admitted for observation.
"Tonight could have been much worse," Pennsylvania Governor Josh Shapiro said during a news conference at Penn State Health Milton S. Hershey Medical Center.
WATCH: Gov. Shapiro gives update on midair crash involving police helicopter
Gov. Shapiro gives update on midair crash involving police helicopter
Shapiro also spoke with the troopers' families.
"I expressed to them, on behalf of all 13 million Pennsylvanians, how thankful we are for their service every day and how our prayers were all answered that they are going to be okay," Shapiro said.
The FAA was on the scene Wednesday night, and the NTSB arrived overnight.
State police said investigators have secured video and photographs that could help reconstruct the collision.
Officials said this airport does not have an air traffic control tower. Instead, pilots share a radio frequency to listen and talk to each other.
Investigators will examine communications on that frequency as part of their inquiry.
Shapiro said he contacted U.S. Transportation Secretary Sean Duffy to request that the FAA expedite its response to the scene.
The cause of the collision remains under investigation.