The Kurdish chief of the civil defence force in the northern oil centre of Kirkuk and his family were killed on early Saturday in a drive-by shooting, police said.
"Assailants opened fire on his car at 8:50 a.m. (0450 GMT) in the city centre. General Saber Mohammed Saber was shot dead on the spot," said Kirkuk police chief Shirku Shaker Hakim.
Saber's wife, sister and son were taken to hospital, where they later died, Hakim added. The driver of the car was seriously wounded.
Three civilians were wounded in the second consecutive day of fighting between Shia militiamen and US troops in Kufa, despite a cease-fire agreement, medics said.
"Last night, it was calm, but this morning at 9:00 (0500 GMT) US troops were out in force and opened fire from their tanks on the Kufa bridge at Mehdi Army positions," said militia source Sheikh Mohammed Ghazawi.
Fighters loyal to cleric Moqtada Sadr, whose private Mehdi Army has been waging an uprising against US-led coalition troops for nearly two months, retaliated, he added.
An AFP correspondent said Sadr's fighters fired mortars and other artillery from the wall of a mosque at US positions on the bridge.
The three wounded were treated at the Furat Awssat hospital in the neighbouring holy city of Najaf, emergency ward doctor Mohammed Abdulkadhim said. He confirmed that they were civilians hurt in the Kufa clashes.
Streets were deserted early Saturday as residents stayed at home and armed militiamen prowled the city.
In Najaf, militiamen still appeared firmly in control of the area around the city's revered Hazrat Ali (RA) mausoleum, despite a less visible presence than in recent days.
About half a dozen militiamen were deployed along the main streets leading to the shrine, carrying assault rifles and rocket-propelled grenade launchers, said an AFP correspondent.
But elsewhere, daily life was easing back towards a semblance of normality as many shops re-opened.