Separate helicopter incidents today claimed the lives of 11 U.S. service-members and three U.S. civilians in Afghanistan, military officials reported. Officials of the NATO-led International Security Assistance Force said four U.S. service-members died when two ISAF helicopters apparently collided over southern Afghanistan, and seven U.S. service-members and three U.S. civilians were killed when their helicopter went down “due to unconfirmed reasons” in western Afghanistan . In addition to the four service-members killed in the apparent collision incident, two more were injured, officials said, adding that hostile fire is not believed to be a factor. In the western Afghanistan incident, the helicopter went down as a combined force in western Afghanistan was departing after a firefight that left more than a dozen enemy fighters dead, officials said. In addition to the 10 U.S. personnel who were killed, 14 Afghan service-members, 11 U.S. service-members and one U.S. civilian were injured. “These separate tragedies today underscore the risks our forces and our partners face every day,” said Army Col. Wayne Shanks, an ISAF spokesman. “Each and every death is a tremendous loss for the family and friends of each service-member and civilian. Our grief is compounded when we have such a significant loss on one day. I can never truly express in mere words our condolences for the families for their loss and sacrifice”.