Croatian Air Force trainer plane carrying an instructor and a trainee crashed near the southern city of Zadar on Thursday, killing both servicemen. In a news conference held only hours later, Defence Minister, Damir Krsticevic, expressed his condolences to families of the men killed, and announced his resignation.

The aircraft, a small Czech-made Zlin-242 twin-seater, crashed near the 93rd Air Force Base in Zemunik, just east of the coastal city of Zadar. Military investigators said that the cause of the crash is yet to be determined.

“Today around 4 pm a Zlin trainer aircraft crashed during a regular training flight, near the village of Donje Biljane. Immediately after the accident, search and rescue teams were dispatched and after arriving at the crash site they confirmed that both airmen, First Lieutenant Marko Novkovic, and Lieutenant Luka Jagetic, had been killed. The cause of the crash is unknown at this moment,” Chief of Staff of Croatia’s Armed Forces, Vice Admiral Robert Hranj, told reporters in a news conference.

Hranj added that the plane has been in use with no problems since 2007, when Croatia had purchased five Zlin-242 trainers. The nearby Zemunik air base is the main base used by Croatian Air Force (HRZ) for training pilots.

First Lieutenant Marko Novkovic was an experienced pilot, and a member of the HRZ aerobatic display team Wings of Storm, and his trainee, Lieutenant Jagetic, had already performed solo flights prior to the fatal crash.

At the same news conference, Defence Minister, Damir Krsticevic, expressed condolences to families of the airmen killed, and made a suprising announcement announcing his resignation.

“Our job is to be with families (of the killed) now, and we will extend all the help and support that we can to them. I would like to express my condolences to all members of the Croatian Air Force and Croatian Army… As of today, I am resigning my post as deputy prime minister and defence minister,” Krsticevic said.

This is the second crash of a military aircraft in little over three months. In late January, an American-made OH-58 Kiowa Warrior helicopter crashed into the Adriatic near the island of Zlarin, killing two airmen on board.

Croatian Air Force had grounded the remaining 15 Kiowa helicopters for three weeks following the crash, and the investigation – which experts said could take as long as a year – has not yet released a report on the cause of the crash.