Police sources told Reuters that at least 33 people were killed by a suicide bomber driving a car and gunmen disguised as police stormed a police headquarters in Kirkuk, northern Iraq.
Kirkuk, a religiously and ethnically mixed area of Arabs, Kurds and Turkman, is at the heart of a dispute over oil and land between Baghdad's central government and the autonomous Kurdistan enclave in the north.
The Sunday morning blast wounded at least 70 more people and police said there were still bodies trapped under the collapsed debris of buildings after the attack.
More top news
The Conservatives have maintained their narrow lead over Labour with less than two days to go before the General Election, a poll suggests
Chester has a proud political legacy. But now this once-safe Tory seat is one of the key 2015 battlegrounds
A Ukip candidate has been suspended two days before the election, as a video emerged apparently showing him threaten to shoot his Tory rival