Riots broke out after demonstrators took to the streets in the city district of Rahimawa to protest a lack of basic services and fuel.
Police say they have imposed a curfew on the northern city until early on 2 January.
Elsewhere in Iraq, insurgents on 1 January blew up a pipeline bringing crude oil from the south of the country to a Baghdad refinery, sparking a large fire.
An Oil Ministry spokesman, Assim Jihad, said the attack had affected but not halted production at the Dura refinery.
In other violence, more than 30 people were reported wounded in a series of bombings across the country.
Six people -- including four suicide bombers -- were killed, dpa reports.
In a separate incident, the Palestinian Embassy said the teenage son of the Palestinian cultural attache to Iraq was shot dead on 31 December.
RFE/RL's World: 2005 In Pictures
A slideshow of images related to the top news stories of 2005 from throughout RFE/RL's broadcast region with links to RFE/RL's reporting.