Gunmen have shot dead the chief of a central Baghdad police station and at least two other Iraqi policemen during an ambush.
The police chief's brother was at the scene of his death
Insurgents in vehicles fired on the police chief's car as he drove to work.
It comes after two days of violence in which a number of people have been killed and dozens of dead bodies found.
Correspondents say the feeling in Iraq is that the tempo of insurgent attacks is rising again after a lull that followed January's election.
On Wednesday a suicide car bomb attack reportedly carried out by a group linked to al-Qaeda killed at least three and injured more than 20 people in the capital.
The director of a Baghdad hospital was shot dead on his way to work.
Iraq's Planning Minister Mehdi Hafaz also came under fire.
But on Thursday an aide told the Reuters news agency it appeared to be a mistake by foreign security guards, rather than an attack by would-be assassins.
Police also said they had found the bodies of at least 20 people who had been shot dead near the western Iraqi town of Qaim.
One of the dead had an Iraqi police identity card and others may have been national guards, officials said.
It followed the discovery on Tuesday of 15 decapitated bodies on a disused army base south of Baghdad, some of them women and children.
In Thursday's attack, the chief of Salhiyah police station, named as Lt Col Ahmed Abeis, was travelling in the al-Saidiyah neighbourhood of the city when his vehicle was attacked at about 0800 local time (0500 GMT).
Police said gunmen stopped his car, then riddled it with bullets.
One report said insurgents dressed as police and set up a fake checkpoint, before asking the occupants' names and shooting them dead.
The police chief's brother, Kadim, picked up his brother's bloodied shoe at the scene and cried out: "God, what have you done?"
AFP news agency reported that an Iraqi army patrol was hit earlier in the day by a roadside bomb.
One vehicle was damaged but there were no casualties, the agency quoted army sources as saying.