The bombers blew up their explosives-laden car at a police station in a Kurdish neighbourhood of the oil-rich city of Kirkuk on Monday.
Around three dozen police officers were seriously injured in addition to the deaths, police and medical sources said.
Dr Hashim Muhammad of Azadi hospital said the two bombers were also incinerated by the blast.
Almost nothing was left of three of the policemen, he said.
At the site of the blast, arms and legs were strewn across the pavement as black smoke billowed and flames licked the ruins of 15 cars. Firemen fought to put out the fires.
The explosion in the Rahimawa neighbourhood occurred at 08:30 (05:30 GMT) as 400 policemen changed shifts, said the station chief Colonel Adil Zain al-Abidin Ibrahim.
Two people drove up to the station in a white Oldsmobile and the vehicle burst into flames, said Sergeant Muhammad Mortada.
Ibrahim added two men had been arrested near the station for questioning.
Kirkuk, with an ethnic mix of Arabs, Kurds and Turkmen, is the target of resistance attacks against police and paramilitary forces working alongside the Americans.
February has been one of the deadliest months for the US-led occupation in Iraq, as fighters have staged a string of attacks.