An air strike in the southern Iraqi city of Basra has destroyed a house and killed at least one occupant.
The US military said a militant died, but would not confirm reports from Iraqi sources that up to six civilians may also have been killed.
The house is in a militia stronghold of which witnessed fierce clashes during a recent government crackdown in Basra.
Separately, police in northern Iraq said seven people were killed by a car bomb attack at an army checkpoint.
The attack happened in al-Dayah, 25 kilometres from Mosul.
Correspondents say Mosul is believed to be the last major urban area of Iraq where Sunni insurgents linked to al-Qaeda have a substantial presence.
Both incidents were on Wednesday evening.
Iraqi Prime Minister Nouri Maliki says he plans more operations against "criminal gangs", singling out the districts of Sadr City and Shula - both strongholds of the Mehdi Army of radical Shia cleric Moqtada Sadr.
He also told a news conference the government would investigate why some Iraqi troops failed to fight alongside their colleagues during the recent operations against Shia militiamen in Basra.
The US military has already accused some members of the Iraqi security forces of not being up to the task.
In another development, Mr Sadr called for a mass demonstration on 9 April against the US presence in Iraq.
The US military later confirmed that US aircraft had carried out Wednesday night's air raid in Basra.
Military spokesman Lt David Russell said aerial fire had been directed against enemy forces fighting Iraqi troops in the city, where hundreds of people were killed in last week's upsurge of violence.
News footage of the aftermath showed rescue workers searching for survivors in the rubble of the two-storey house.
Hospital officials said three bodies had been received, including two men and an elderly woman. Two women were being treated for injuries.
Witnesses said three people were still feared buried in the rubble.
"While we were preparing for evening prayer, US aircraft bombed this house. We rushed to save survivors but in vain," a neighbour was quoted as saying.
Mr Sadr ordered his Mehdi Army fighters off the streets of Basra and other southern Iraqi cities on Sunday.
Meanwhile, reports from the southern city of Hilla say US forces called in helicopter strikes during a clash with gunmen on Thursday.
Iraqi police are quoted as saying five people were killed in the pre-dawn operation, including four policemen.
Fighting broke out after US troops in civilian clothes entered a central district of Hilla, they said.
US military sources said the clash started after troops went to arrest rogue elements in the Mehdi Army.