DALLAS (AP) — Officials on Monday identified the six men killed in a deadly collision between two vintage military aircraft at a Dallas air show, all of whom were experienced aviators with years of flight training.

The Commemorative Air Force, which put on the show, identified the victims as: Terry Barker, Craig Hutain, Kevin “K5” Michels, Dan Ragan, Leonard “Len” Root, and Curt Rowe. They died Saturday when a World War II-era bomber and a fighter plane collided and crashed in a ball of flames, horrifying spectators who had gathered for the air show that opened on Veterans’ Day.

Several videos posted on social media show the fighter plane flying into the bomber.

All of the men were volunteers, but each had gone through a strict process of logging hours and training flights and were vetted carefully, Hank Coates, the CEO of Commemorative Air Force said at a weekend news conference.

“This is not their first rodeo,” Coates said. These guys are very well versed. Many of them are airline pilots, retired airline pilots, retired military pilots like myself.

“These are very well-trained folks who have been doing this for a long time.”

Officials have not publicly identified which of the victims was piloting the aircrafts.

The National Transportation Safety Board is investigating the collision, including why both aircraft were flying at the same altitude and in the same air space, NTSB member Michael Graham said at a Sunday news conference.

Graham said investigators are analyzing radar and video footage to pinpoint the exact location of collision. He said most of debris from the crash was scattered on the airport property and will be carefully examined, along with audio recordings from the air traffic control tower, pilot training records and aircraft maintenance records.

Neither aircraft was equipped with a flight-data recorder or a cockpit voice recorder, separate devices referred to collectively as the black boxes, and neither were required to have those devices, Graham said.

The crash came three years after the crash of a bomber in Connecticut that killed seven, and amid ongoing concern about the safety of air shows involving older warplanes. The company that owned the planes flying in the Wings Over Dallas show has had other crashes in its more than 60-year history.

Investigators will examine the wreckage from both aircraft, conduct interviews of crews present at the air show and obtain pilot training and aircraft maintenance records.