The Islamic State jihadist group killed a senior Kurdish commander and five fighters Friday in a major attack in Iraq's Kirkuk province, while bombings elsewhere left at least nine dead.
The IS assault on areas south and west of the northern city of Kirkuk began at around midnight, sparking fighting with medium and heavy weapons that was still ongoing Friday morning, a police brigadier general said.
Brigadier General Shirko Rauf and five other members of the Kurdish peshmerga forces were killed in clashes and 46 more were wounded, the police officer and a doctor said.
Atif al-Najjar, a commander in the Badr militia, said that 500 volunteer "popular mobilisation" fighters have moved from the town of Tuz Khurmatu to positions in three areas south of Kirkuk to help defend against IS.
The Kirkuk province security committee announced a curfew beginning at 10:00 am (0700 GMT) on Friday, saying it will be in effect until further notice.
A car bomb also exploded near security headquarters in central Kirkuk city, wounding five people, a police colonel and the doctor said.
According to the colonel, suicide bombers who were also armed with other weapons tried to take up positions on the roof of a hotel in the city, but were killed by security forces before they could do so.
Violence also struck Samarra, home to a revered Shiite shrine that was bombed in 2006, setting off a wave of Sunni-Shiite sectarian violence that killed tens of thousands of people.
One suicide bomber detonated a car bomb at a police checkpoint at an entrance to the city, while two more struck a police headquarters inside it, killing four police and wounding nine.
Another bomber was shot dead, and sporadic clashes between security forces and IS also took place west of Samarra, police said.
In Baghdad, at least one bomb exploded in a used clothes market in the central Bab al-Sharji area, killing at least five people and wounding at least 17, officials said.
IS spearheaded a sweeping offensive that has overrun much of Iraq's Sunni Arab heartland since June, presenting both an opportunity for territorial expansion and a threat to the country's three-province autonomous Kurdish region.
Several Iraqi divisions collapsed in the early days of the offensive, clearing the way for the Kurds to take control of a swathe of disputed northern territory that they have long wanted to incorporate into their region over Baghdad's objections.
But after driving south towards Baghdad, IS turned its attention to the Kurds, pushing them back towards their regional capital Arbil in a move that helped spark US strikes against the jihadists.
Bolstered by the air strikes as well as international advisers and trainers, Kurdish forces have clawed back significant ground from IS.
The conflict is redrawing some of the de facto internal boundaries of Iraq in favour of broader Kurdish control in the north.