Officials say three American servicemembers who went missing during a training mission last week in Lithuania have been found deceased. A fourth soldier in the group is still unaccounted for.

The U.S. Army Europe and Africa announced Monday that the bodies of the three servicemembers — assigned to the 1st Armored Brigade and Combat Team, 3rd Infantry Division — were found in their armored vehicle submerged in swampy terrain in the eastern part of Lithuania near bordering Belarus.

IN CASE YOU MISSED IT | Four American soldiers who went missing in Lithuania have reportedly died

Officials said it took "tremendous resources" to recover the 63-ton-vehicle from the peat bog, including helicopters, unmanned aerial systems, excavators, and other heavy machinery. Search and recovery operations are still ongoing for the fourth missing soldier.

“The Soldiers we have lost in this tragedy were not just Soldiers - they were a part of our family. Our hearts are heavy with a sorrow that echoes across the whole Marne Division, both forward and at home,” Maj. Gen. Christopher Norrie, 3rd Inf. Div. commanding general said in a statement. “We stand in grief with the families and loved ones of these extraordinary ‘Dogface Soldiers’ during this unimaginable time. But the search isn’t finished until everyone is home. Words cannot express our gratitude to those still working around the clock during these extensive search and recovery efforts and your unwavering commitment not to rest until all are found.”

Officials announced the soldiers went missing on March 26 while on a scheduled mission to recover an immobilized tactical vehicle. Shortly thereafter, it was reported that NATO Secretary General Mark Rutte confirmed they had died but did not offer any additional information.

The U.S. Army and Lithuanian authorities continue to investigate the cause of the incident. Officials said a dive team is is using "ground penetrating radar" to assist in the search for the fourth missing servicemember.

Officials said the soldiers were deployed to Lithuania as part of Operation Atlantic Resolve and were permanently stationed at Fort Stewart in Georgia.