BAGHDAD (Reuters) - Five U.S. soldiers were killed, including four in a single explosion, during combat operations south of Baghdad on Saturday, the U.S. military said on Sunday.

Four other soldiers were wounded in the explosion but no other details of the incident were immediately available.
In a separate statement, the U.S. military said a fifth soldier had been killed by small arms fire while on foot patrol southeast of Baghdad on Saturday.
The U.S. military said the soldiers were part of Task Force Marne, which has deployed in areas south of Baghdad to stop the flow of weapons, explosives and militants into the capital.
About 30,000 extra troops have been sent to Iraq since February as part of a security crackdown designed to buy time for Baghdad's fractured coalition government to meet a series of political targets set by Washington.
The five deaths bring to at least 3,689 the number of U.S. troops killed in Iraq since the 2003 U.S.-led invasion to topple Saddam.
At least 31 U.S. soldiers have been killed so far in August.
Lieutenant-General Raymond Odierno, the U.S. military's second-in-command in Iraq, said on Saturday there had been a decline in troop deaths after a sharp spike in May and June.
He said troop deaths were roughly on par with July, when 80 soldiers were killed.
U.S. commanders have warned of a likely rise in U.S. casualties as troops push into dangerous areas previously off limits to U.S. forces.
They also fear more attacks on U.S. soldiers by Shi’ite militias and al-Qaeda Sunni Arab militants ahead of the presentation of a key report on Iraq to Congress in mid-September