VILNIUS, Lithuania (TNND) — The four U.S. soldiers that went missing at a training area out Lithuania’s capital have died, according to NATO Secretary General Mark Rutte.

Rutte told reporters during a trip to Warsaw that he had received word about the deaths of the soldiers, according to The Associated Press.

“This is still early news so we do not know the details. This is really terrible news and our thoughts are with the families and loved ones,” Rutte said.

The soldiers were conducting scheduled tactical training when they went missing, the U.S. Army, Lithuanian Armed Forces and Lithuanian law enforcement officials said in a statement.

Officials said the soldiers are from the 1st Brigade, 3rd Infantry Division.

The Lithuanian military said the American soldiers and their vehicle were reported missing Tuesday afternoon during an exercise at the General Silvestras ukauskas training ground in Pabrad.

Air Force helicopters and the State Border Guard were being used to search a “potential accident site.”

“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, the V Corps commanding general said. “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.”

Lithuania, a NATO member, is a staunch ally of Ukraine in its war against Russia.

Further information will be provided as new details become available.