The American pilot aboard a Ukrainian Air Force fighter jet killed when the aircraft crashed during a training exercise in Ukraine on Tuesday now has been identified as hailing from California, officials said.

An Air Force fighter pilot, Lt. Col. Seth “Jethro” Nehring, was with the California Air National Guard’s 194th Fighter Squadron, part of the 144th Fighter Wing based in Fresno.

Nehring had been a member of the 144th for more than 20 years. He began his career as an enlisted crew chief before being selected for a pilot slot; he flew the F-16 Viper for more than 15 years and converted to the F-15 Eagle, the Air Force said.

“We are a close-knit family and when a tragedy like this occurs, every member of the 144th Fighter Wing feels it,” Col. Daniel Kelly, commander of the 144th FW, said to Fox News in a statement. “We share in the sorrow felt by Jethro’s loved ones and our thoughts and prayers go out to his family and friends as well as those of the Ukrainian aviator.”

Officials said Nehring and a Ukrainian pilot were killed in the crash, which took place in the Khmelnytskyi region in western Ukraine, 175 miles southwest of the capital of Kiev.

The crash took place during joint military training between the U.S. military and Ukrainian counterparts, known as Clear Sky 2018, as Fox News previously reported.

The joint military training was billed as the "first-ever Clear Sky exercise," to be held primarily at Starokostiantyniv Air Base in Ukraine as well as other training areas and ranges in the region.

Personnel from nine nations are taking part in the exercises that started in Ukraine on Oct. 8.

The U.S. and Ukrainian governments are conducting an investigation to determine the cause of the crash, officials said.

Fox News’ Jennifer Griffin and Lucas Tomlinson and The Associated Press contributed to this report.