Daesh gunmen on Wednesday opened fire and later blew themselves up in the Iraqi city of Tikrit, killing at least 31 people and wounding 42.
The militants, who were disguised as police officers and driving a police car, targeted a police checkpoint and a police colonel's home.
Iraqi police said there were around 10 attackers, including two suicide bombers.
Daesh's Amaq news agency said seven suicide fighters attacked a police position and the home of the head of the city's counter-terrorism service, who was killed.
The assailants blew themselves up when they ran out of ammunition, it said.
A total of 31 bodies were taken to hospital, including 14 policemen, said Nawfal Mustafa, a doctor at the city's main hospital.
The death toll rose during the morning as the bodies of civilians killed in shops were found.
A police colonel was killed with four members of his family after his house was attacked.
Two suicide attackers detonated their vests when surrounded by police, and three others were killed in separate clashes.
Five militants are thought to be hiding and police declared a curfew on Wednesday, they said.
A US-backed offensive is underway to dislodge Daesh from the remaining districts under its control in Mosul, 225 km away, the group's last major urban stronghold in Iraq.
Iraqi forces and Iranian-backed Shia militias drove the militants away from Tikrit two years ago.
Tikrit is the home city of Saddam Hussein, the former president of Iraq who was toppled during the 2003 US-led invasion of Iraq.