Two helicopters collided Monday in southern Afghanistan, killing four American troops and injuring two, the military said.
A third US helicopter crashed in a separate incident in the west, leaving "some dead," US military spokeswoman Elizabeth Mathias said. She did not have details on how many or their nationalities.
It was unclear what caused the collision in the south. US military spokesman Col. Wayne Shanks said the military had ruled out hostile fire but he did not have any other details. He said the injured had been evacuated to hospitals inside Afghanistan.
The third helicopter went down during an operation by Afghan and international forces in which a dozen militants were killed, the military said. It said the crash happened in western Afghanistan without giving a more precise location.