"All of the wounded soldiers were evacuated to a combat support hospital following the attack. One soldier has returned to duty," the statement said.
The deaths take the number of US troops killed in Iraq to 99 so far this month, according to icasualties.org, a Web site that tracks military tolls.
That is lower than the 126 US soldiers who died in May, but still makes it one of the bloodiest months for U.S. forces in Iraq this year.
US President George W Bush has sent 28,000 extra troops mainly to Baghdad to help curb bloodshed and buy time for Shi'ite Prime Minister Nuri al-Maliki to reach a political accommodation with disaffected minority Sunni Arabs, who are locked in a cycle of violence with majority Shi'ite Muslims.
A total of 157,000 US troops are now in Iraq.
US commanders have warned of increased casualties as more soldiers deploy in and around the capital.