Thousands of Shia Muslims poured onto the streets
Large crowds of Iraqi Shia Muslims have demonstrated against US troops in the capital Baghdad, accusing them of defiling a religious school.
The protests, involving thousands, were triggered when the crew of an American helicopter flying close to the school's communications tower appeared to try to tear down an Islamic flag.
An Iraqi civilian was killed after US troops opened fire on the demonstrators who started throwing stones and chanting "No, no to America".
Earlier on Wednesday, two US soldiers were killed in ambushes in Iraq and two gunmen were reportedly also shot dead.
One soldier was killed and one wounded in a roadside bomb attack at Dawar, south of Saddam Hussein's hometown of Tikrit.
The protests by stone-throwing crowds in Baghdad were a rare show of anger by the Shia Muslim community which has mainly welcomed the overthrown of the former regime.
Shia cleric Sheikh Qays in the Sadr City area of the capital said US troops had defiled a sacred place and the crowds demanded they stay away.
"We request that no American soldier enter this city," he said.
"The presence of American soldiers shakes security and causes terrorism. This is an aggression on the sacred Muslim places," he told Reuters new agency.
A US spokesman said 'helicopter wash' blew down the banner
Hassan Azab, a member of the district council, said: "We're peaceful people, but one edict (from the imams) and the entire American Army will become our prisoner."
US military spokesman Sergeant Danny Martin told the Associated Press news agency it appeared rotor wash from the Black Hawk helicopter blew down the banner.
He said the US forces opened fire on the protesters only after stones, gunfire and one rocket-propelled grenade were directed at the soldiers of the 1st Armoured Division.
One civilian was killed and four were wounded, he said. He said no soldiers were hit.
The death of the US soldier in Dawar brings to at least 58 the number of American troops killed by hostile fire since major combat operations were declared over by President George W Bush on 1 May.
Coalition sources estimate there are about 12 attacks a day on American soldiers in Iraq.
In another clash on Wednesday, the US military reported that troops had killed two Iraqi gunmen in the Baqubah region, north-east of Baghdad.