Ten people were killed and more than a dozen others were injured during a NATO training exercise in Spain.

Reuters noted that the defense ministry said a Greek F-16 fighter jet experienced power failure while taking off from a training facility at Los Llanos Airbase in Albacete on Monday.

“The plane, part of the Tactical Leadership Program of NATO was carrying out a [training] exercise when during the takeoff the plane lost power, crashing into the parking area for planes, crashing into various planes that were parked there,” Spain’s defense ministry said in a statement.

NBC News reported that as many as six American soldiers are among the injured. Their injuries, however, are said to be non-life threatening.

Personnel from several countries including the U.S., Denmark, Germany, Belgium and the U.K. are stationed at the base.

NATO Secretary General Jens Stoltenberg said that he was “deeply saddened” by the crash and expressed condolences to the families of the deceased.

The crash is being investigated.