A U.S. Black Hawk helicopter with four crew members on board crashed in southwestern Afghanistan on Thursday.
A senior U.S. military official confirmed to NBC News that there was bad weather in the area at the time of the crash, but said that the possibility that enemy activity downed the helicopter could not be ruled out.
A senior source with the International Security Assistance Force in Kabul told NBC News that no confirmed reason for the crash was available.
Other than the four crew members, no passengers were believed to be on board.
"We don't expect any survivors," the official told NBC News.
The Blackhawk was traveling with another helicopter at the time, though the second helicopter did not experience any problems.
A ferocious 18-hour Taliban attack on the Afghan capital ended when insurgents who had holed up in two buildings were overcome by heavy gunfire from Afghan-led forces and pre-dawn air assaults from U.S.-led coalition helicopters. ITN's Bill Neely reports.
Reuters, citing a U.S. defense official, said that the helicopter went down in the Regional Command-Southwest area, which includes the traditional Taliban stronghold of Helmand province.
Despite a resilient insurgency, the United States, like its NATO allies, plans to withdraw most of its combat troops from the country by the end of 2014.
Jim Miklaszewski is the chief Pentagon correspondent for NBC News; Courtney Kube is the Pentagon producer for NBC News. Reuters also contributed to this report.
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