The two U.S. Forces-Afghanistan service members were killed when a person wearing an Afghan National Police uniform opened fire on them in Khas Uruzgan in the southern province of Uruzgan, the International Security Assistance Force said in a release.
Attacks on coalition troops by people in Afghan uniforms are often referred to as "insider" attacks.
Another ISAF soldier was killed in an attack by insurgents in western Afghanistan, coalition officials said.
The ISAF did not reveal the identities of the victims or the exact locations of the incidents in keeping with its policy of deferring identification procedures to the relevant authorities.
Khaama Press said at least 278 U.S. troops have been killed in incidents across Afghanistan since the beginning of this year.