Six Americans assigned to a U.S. coalition in Afghanistan reportedly were killed when a suicide bomber detonated a bomb near Bagram Air Base.
Three more Americans were reportedly injured, U.S. officials said.
The Taliban went on Twitter to claim responsibility for the attack, the Hill reported.
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"We're deeply saddened by this loss," said Brig. Gen. Wilson Shoffner, a spokesman for the coalition forces, in a statement. "Our heartfelt sympathies go out to the families and friends of those affected in this tragic incident, especially during this holiday season."
The troops were officially listed as members of the NATO team, but military members speaking on condition of anonymity verified they were all Americans.
Bagram is located just north of Kabul, the capitol of Afghanistan.
NBC News reported the suicide bomber rode up on a motorcycle and detonated alongside a convoy.