Meanwhile, US and Iraqi soldiers in Baghdad detained about 20 people suspected of posing a "security threat" in a large operation near the health ministry, a military official said on Wednesday.
Police General Hikmat Mahmud Muhammad was shot dead by three men in a car as he left his home at 7:30am (04:30 GMT) in Mosul, 370km north of the capital, said Lieutenant Colonel Abd al-Azil Hazim Khafudi.
"The general died in a hail of bullets and the assailants escaped," Khafudi said.
And in the latest vigilante killing of a former Baathist, Anfal Ilah al-Anaz, a general in Saddam's army, was assassinated and his son badly wounded in Mosul on Tuesday at 10:00pm (19:00 GMT).
Some men pulled up in a white Opel and riddled his car with bullets, said police Major Makram Zakaria. Anaz was hit in the chest and back, while his son, a former intelligence officer, was hospitalised, Zakaria added.
Dozens of former Baathists have been killed since Saddam's regime was toppled by the Americans last April.
Elsewhere, US soldiers and Iraqi civil defence officers in Baghdad sealed off an area of the city between Russafa bridge and the health ministry with tanks and barbed wire, AFP reported.
US-led forces arrested an imam
and 20 worshippers in Baghdad
Captain Buckley O'Day said about 20 people "suspected of being a security threat in Iraq" were being held for questioning.
Two policemen near the scene said they saw troops arrest the main cleric of a local mosque along with 20 other worshippers.
In another incident, a group of US soldiers backed by helicopters raided Saad bin Abi Waqqas mosque and the house of Shaikh Abd Allah al-Janabi, imam of Falluja mosque, Aljazeera's correspondent reported.
"Residents said al-Janabi is wanted by the US forces as his speeches were calling for Jihad and resisting occupation," the correspondent added.
Separately, a previously unknown group, calling itself Katab al-Mujahidin claimed Monday's car bombing of a police station in the ethnically tense city of Kirkuk that killed 10 policemen.
A car bomb in the fractious city
killed 10 people on Monday
Police said they obtained a copy of a pamphlet circulating in areas around Kirkuk, which has been riven by feuds among its volatile mix of Kurds, Arabs and Turkmen. The pamphlet threatens attacks on all Iraqis working for the US-backed security forces.
"Any Iraqi proved to be supporting or assisting the Americans will be sentenced to death. Muslim brothers do not serve the Americans. Your spirit is being corrupted by US dollars," it read.
Meanwhile, a group of Turkmen demonstrated before the headquarters of the Governing Council in Baghdad, Aljazeera's correspondent reported.
The demonstrators were calling for greater representation in legislative and executive bodies, in line with a provisional law due to be enacted at the end of February.
They also called for a constitution guaranteeing their rights and maintaining the ethnic identity of Kirkuk, which has a large Turkmen minority.