The pilot of a United States Air National Guard was killed Tuesday when the Ukranian Su-27UB fighter jet crashed in west-central Ukraine field, according to Ukrainian General Staff reports.

A Ukrainian Su-27UB twin-seat combat trainer / fighter jet with two pilots crashed during a training exercise on Tuesday.

The accident occurred at around 5:00 PM local time on Oct. 16, 2018, near the village of Ulaniv, which is situated approximately 185 miles southwest of the Ukranian capital Kyiv.

Also reported that both the pilot and co-pilot have been killed after a Su-27UB (70 Blue) fighter jet crashed during a Clear Sky 18 training flight in west-central Ukraine.

According to the Ukrainian General Staff, the bodies of two pilots were found: one was a pilot of the Ukrainian Air Forces, the second – a US Air Force National Guard pilot.

“We regret to inform that according to the rescue team, the bodies of two pilots have been discovered: one is a serviceman of the Ukrainian Air Force, the other is a member of the US National Guard,” it said.

U.S. Air Force public affairs officer said: “We are aware of a Ukrainian Su-27UB fighter aircraft that crashed in the Vinnytsia region at approximately 5pm local time during Clear Sky 2018 today.”

“We have also seen the reports claiming a U.S. casualty and are currently investigating and working to get more information. We will provide more information as soon as it becomes available.”

Later, U.S. Air Forces in Europe (USAFE) has confirmed that a U.S. service member was involved in the incident, but has no made an official announcement as to their status. USAFE also said that mishap is already under investigation.

The Su-27UB jet was taking part in Clear Sky 2018, a joint military exercise with NATO members taking place October 8 through 19 in Western Ukraine.

Clear Sky 2018 is a joint and multinational exercise that involving approximately 950 personnel from nine nations, including Belgium, Denmark, Estonia, the Netherlands, Poland, Romania, Ukraine, the United Kingdom, and the United States.

The Clear Sky 18’s training is intended to increase the level of interoperability of the Air Forces of the Armed Forces of Ukraine with the Air Forces of the US and NATO, work out effective joint management of operations in the air, work out the sharing of intelligence and surveillance capabilities, as well as cyberdefense focused on the needs of the air forces.