Anti-US fighters set police stations ablaze, stole weapons and held streets in Mosul today in Iraq's third largest city, residents said.
Explosions and fire from assault rifles and rocket-propelled grenades could be heard, and columns of smoke rose from at least two police stations set alight.
The northern city of Mosul has seen frequent outbreaks of violence, but residents and reporters said the past two days were the worst since the end of the war last year.
As US forces battle to suppress insurgents in the rebel city of Fallujah, it appears many fighters may have fled to other cities where they are launching new attacks.
In the past three days, there has been a step up in guerrilla activity in Samarra, Baiji, Baquba, Tikrit, Ramadi, areas of Baghdad and in the holy city of Kerbala to the south.
In Mosul, a city of about three million people, insurgents attacked a group of Iraqi National Guardsmen blocking a bridge in the city centre, killing five of them and destroying three vehicles, witnesses said.
A cameraman working for Reuters filmed groups of militants emerging from a police station carrying police-issued AK-47s and bullet-proof jackets before setting the building on fire.
A photographer working for Reuters covering the aftermath of one attack was shot in the leg and taken to hospital.
Doctors said one civilian had died and at least 25 had been wounded by crossfire in the past two days of fighting.