The wounded -- four U.S. service members and two U.S. civilians -- were treated at a medical facility inside Bagram Air Field, located about 25 miles north of Kabul.
The Taliban claimed responsibility for the attack on Bagram, the Los Angeles Times reported, noting the rocket attack was the third to penetrate Bagram since January.
The attack brought the U.S. death toll in Afghanistan to at least 81 so far this year, reported icasualties.org, a private Internet site that tracks combat deaths. At least 94 U.S. soldiers have died in combat in Iraq so far this year, the site said.
Sunday's attack came just hours after two U.S. National Guard soldiers were killed by a roadside bomb in Kandahar and a U.S. soldier was killed by insurgents in eastern Afghanistan, the Times reported.