That is reported by Reuters and relayed by Ukrinform.
"Whilst I was speaking the news came out about four American soldiers who were killed in an incident in Lithuania," Rutte told reporters in Warsaw.
He added that he did not know any further details about the tragedy.
Pabradė is located less than 10 kilometers from the Belarusian border.
Earlier, the Lithuanian Armed Forces announced that on Tuesday, after training at the Pabradė training ground, four U.S. soldiers went missing.
According to the military, the report of the missing soldiers and one tracked vehicle at the General Silvestras Žukauskas training ground came in on Tuesday at 16:45.
The soldiers, from the 1st Brigade of the 3rd Infantry Division, were conducting scheduled tactical exercises.
