A helicopter belonging to the NATO-led international security force in Afghanistan has crashed in the west of the country, killing 17 Spanish troops.
Officials say a second helicopter also made an emergency landing and an unspecified number of troops on board were believed to be wounded. Rescuers are now at the site near Herat, recovering the dead and wounded.
Spanish Defense Minister Jose Bono said it could have been an accident, but he can not rule out an attack from the outside.
But an Afghan intelligence official, whose troops are providing security in the area, says the two choppers came too close together while flying and the rotor blade of one hit the other.
Officials say both choppers were on a training mission to support legislative elections next month.
Information for this report is provided by AP, AFP and Reuters.