The Gulf of Mexico witnessed an unusual incident on Wednesday afternoon, when two U.S. Force F-15Cs supposedly collided during a training mission, officials announced. The incident took place near Panama City in Florida just days after the Air Force gave green light to what most consider to be an aging fleet.

Hours after the incident, Air Force officials were still unable to establish the cause of the crashes. The two jets were reported missing around 2 p.m., but no one was able to say whether they collided or crashed separately.

The Coast Guard rescued both pilots, who managed to eject from the crashing planes. Unfortunately, only one of them still has chances of recovery, while the other one didn’t survive the incident and passed away at the hospital. Officials named a board of officers to investigate the crash.

The planes collided approximately 50 miles (80 Km) south of the Tyndall Air Force Base, after losing radio contact with base. Both of them were based at Eglin Air Force Base, near Fort Walton Beach and belonged to the 33rd Fighter Wing.

“The 33rd FW Nomads and Team Eglin have suffered a great loss today and my heart goes out to the family and friends of our former airman,” Wing Commander Col. Todd Harmer said in a statement. “We will continue to do everything we can do to assist our families and airmen at this tragic time.”

Air Force officials started an investigation on all F-15s in November 2007, after a 30-year-old F-15C ripped apart during a training mission. Pentagon decided to ground all planes until the safety of all of them was to be established.

Unfortunately, this particular incident took place less than a week after the Air Combat Command cleared all F-15s that had been previously grounded and declared them safe. Officials will investigate the cause and circumstances of the accident before making another public statement.