At least 33 people have been killed in two co-ordinated suicide car bombings and a gun attack in northern Iraq.
A car bomb went off at the city's telephone exchange building and simultaneously at a police base.
Two militants dressed in police uniforms and armed with guns, grenades and suicide vests also stormed the police compound in the city of Kirkuk.
A further 70 people were injured in the rush-hour attacks - shattering a relative calm in recent days in the war-torn country.
Police said there were still bodies trapped under the collapsed debris of buildings following the explosions.
The gunmen burst through the main gates of the police base in the direction of the headquarters block.
They threw several grenades, but were killed before they could get there, witnesses said.
"I saw a vehicle stop at the checkpoint at the main entrance, and the police started checking it," said Kosrat Hassan Karim, who was nearby when the attack took place.
"Suddenly, a loud explosion happened, it was terrifying.
"I saw many people killed inside their cars."
No group immediately claimed responsibility.
Police said the dead included 12 employees at the government office. But a health official said only 16 bodies were at a hospital morgue.
Kirkuk, an ethnically mixed city, is at the centre of a dispute over oil and land rights between Baghdad's central government and the autonomous northern Kurdish region.
The unresolved row is persistently cited by diplomats and officials as the biggest threat to Iraq's long-term stability.
Tensions between Shi'ite, Kurdish and Sunni factions in Iraq's power-sharing government have been on the rise this year.
Militants continue to carry out almost daily strikes, with at least one big attack a month.
Last month a suicide bomber disguised as a mourner killed at least 26 people at a funeral at a Shi'ite mosque in the nearby city of Tuz Khurmato.
Days earlier, a suicide bomber driving a truck killed 25 people in an attack on a political party headquarters in Kirkuk, which is 105 miles north of the capital Baghdad.