Four U.S. Army soldiers went missing while on a training mission in Lithuania, prompting a search for their vehicle, military officials said on Wednesday.

The soldiers, all from 1st Brigade, 3rd Infantry Division, had been conducting scheduled tactical training in a training area near Pabrade, a city in eastern Lithuania, near the border with Belarus, the U.S. military said.

The U.S. Army, Lithuanian Armed Forces, Lithuanian law enforcement officials and others were looking for the soldiers, the U.S. military said, adding that “search and recovery efforts are underway.”

The Lithuanian military said that the American soldiers and their vehicle were reported missing on Tuesday at about 4:45 p.m. It said that Air Force helicopters and other resources were being used to search a “potential accident site” in the Pabrade training area.

“I would like to personally thank the Lithuanian Armed Forces and first responders who quickly came to our aid in our search operations,” Lt. Gen. Charles Costanza, commanding general of the V Corps, a U.S. Army unit that operates along NATO’s eastern flank, said in a statement on Wednesday. “It’s this kind of teamwork and support that exemplifies the importance of our partnership and our humanity regardless of what flags we wear on our shoulders.”

The U.S. military often conducts training missions in Lithuania, a NATO member and staunch ally of Ukraine in its war against Russia. Many of those exercises are held at the Pabrade training area, and involve soldiers from Lithuania and other NATO allies. Nearby Belarus is a close ally of Russia.