Military officials said NATO troops shot the man soon after he opened fire on a group of coalition troops, The Washington Post reported.
A military spokesman said officials were investigating whether the shooter was an Afghan soldier or a civilian wearing an Afghan army uniform.
No other details were released, the Post said.
Relations between Afghan forces and interntional troops have become strained fllowing several incidents this year, including the accidental burning of Korans by U.S. military personnel last month.
U.S. Defense Department statistics indicate at least 51 NATO troops have been killed by Afghan security personnel since May 2007. Nine of the deaths occurred after the Koran burnings.