The attack shatters a relative calm in recent days in Iraq, which has been grappling with a political crisis.
Suicide attack on Iraq police HQ kills 30
KIRKUK, IRAQ // A suicide car bombing followed by an assault by grenade-throwing gunmen on a police headquarters killed 30 people today in a disputed city in northern Iraq.
The vehicle that was detonated in central Kirkuk was painted to appear as though it was a police car, and the militants who sought to seize the compound were dressed as policemen, witnesses said.
The attack shattered a relative calm in recent days in Iraq, which has been grappling with a political crisis pitting the prime minister, Nouri Al Maliki, against his erstwhile government partners amid weeks of continuing protests calling for him to resign, less than three months before key provincial elections.
No organisation immediately claimed responsibility for the attack, but Sunni militants including Al Qaeda's front group in Iraq frequently target security forces and government targets in a bid to destabilise the country and push it back towards the sectarian bloodshed that blighted it from 2005 to 2008.
The initial suicide car bomb was set off during morning rush hour, and was quickly followed by three gunmen dressed in police uniforms, armed with hand grenades and suicide vests, bursting through the main gate of the Kirkuk police compound in the direction of the headquarters building.
They threw multiple grenades as they sought to reach the building, but were killed before they could get there, witnesses said.
Brigadier General Natah Mohammed Sabr, the head of Kirkuk city's emergency services department, put the toll at 30 dead and 70 wounded.
In addition to the casualties, the attack caused massive damage to nearby buildings and shops.
The massive explosion also killed people in nearby buildings. Mohammed Aziz, who works in an office building adjacent to the police headquarters, said at least two of his colleagues died in the blast.
Kirkuk, an ethnically mixed city, lies at the heart of a swathe of disputed territory claimed by both the central government and Iraq's autonomous northern Kurdish region.
The unresolved row is persistently cited by diplomats and officials as the biggest threat to Iraq's long-term stability.
* Agence France-Presse