Reporting from Kabul, Afghanistan — A helicopter crash in volatile southern Afghanistan killed three U.S. service members and a civilian employee, the Western military said Friday.
The overnight crash in Zabul province also injured "numerous" others aboard, NATO's International Security Assistance Force said in a statement. It identified the craft as an Air Force CV-22 Osprey, which it said is used for long-range infiltration and resupply.
The Taliban claimed to have shot down the chopper, but insurgents routinely issue such boasts whenever any Western aircraft goes down.
NATO said the cause of the crash was not immediately known. Officials did not identify the branch of service of those who were killed or disclose anything about their mission.
Zabul borders Kandahar province, which is to be the venue for a major Western military offensive over the summer. It also shares a border with Pakistan, with numerous Taliban infiltration routes along the porous frontier.
Insurgents are active throughout Zabul, military officials have said.
NATO did not immediately say whether its forces had been able to secure the scene of the crash and remove the downed helicopter, which is fitted with an array of sophisticated gear.
The Western military said the injured were taken to a nearby military base for treatment. The crash occurred about seven miles west of Zabul's capital, Qalat.
NATO forces rely heavily on helicopters because Afghanistan's roads are so bad and its distances so great. But in more than eight years of fighting, the Taliban have only rarely been able to down Western aircraft with missiles or rockets.
Mechanical failure and weather-related problems are much likelier causes of crashes. But insurgents did manage to shoot down a Chinook helicopter five years ago, killing 16 U.S. troops.
U.S. battlefield casualties have spiked in the first quarter of this year, with deaths roughly doubling from the same period a year ago.
The largest proportion of deaths and injuries occur in Afghanistan's south, where the insurgency is at its strongest. Improvised explosive devices, or IEDS, are the biggest single killer of Western troops.