The attacker, reportedly dressed as a policeman, drove his bomb-laden car into a crowd of around 100 officers who were lining up for morning roll call.
"I couldn't run away. I saw dozens of dead bodies and pieces of flesh -- all belonging to my colleagues -- and the whole area was full of the smell of blood and burned flesh," wounded police officer Faryard Khorsheed told a Washington Post reporter.
The Irbil bombing coincided with a number of other attacks across Iraq on Sunday and Monday, which killed some 70 people, including an American soldier.
On Sunday, a suicide bomber killed 23 Iraqis at a kebab restaurant just outside Baghdad's heavily fortified green zone.
On Monday, intense fighting broke out in southwest Baghdad when insurgents attacked an American military patrol around 5:30 a.m. Insurgents reportedly waited for Iraqi reinforcements to arrive before detonating a car bomb and then raining mortar and rocket fire onto a nearby police station, according to the Post. Four policemen and one Iraqi soldier were reportedly killed in the fighting.
In another attack on Monday, a U.S. soldier was killed in a roadside bombing in Tal Afar, 90 miles east of the Syrian border.
Militants also claimed to have killed a contractor working for an American company and his Iraqi guards after capturing them in a raid on a convoy. The report was unconfirmed by Iraqi and American officials.