Baghdad (CNN) -- Twenty-seven people were killed and 84 wounded in three blasts in the oil-rich city of Kirkuk on Thursday, officials said.
Two car bombs and a roadside bomb exploded in central Kirkuk, about 240 kilometers (149 miles) north of Baghdad.
The first bomb exploded in a car parked near police headquarters in central Kirkuk. A few minutes later, when Iraqi security forces arrived at the scene, a second car bomb exploded and caused most of casualties.
Iraqi police and Kurdish security forces were among those killed. Civilians also were injured and killed, because many had gathered out of curiosity after the first explosion, police said.
Twenty minutes later, a roadside bomb exploded near an Iraqi police patrol by the governorate building in central Kirkuk.
The attacks bear the hallmark of an al Qaeda group in Iraq, police said.
The U.N. secretary-general's special representative for Iraq, Ad Melkert, condemned the attacks and extended his condolences to the victims and their families.
The ethnically mixed city of Kirkuk is about 240 kilometers (about 150 miles) north of Baghdad.The killing of Osama bin Laden in early May offered some peace and closure, but the road ahead is long, Maj. Gen. Jeffrey Buchanan, a spokesman for U.S. Forces-Iraq, told CNN this month.
"We have a lot of work to do in ... what we are facing every day in Iraq. We have a lot of work to do with al Qaeda in Iraq," he said.As U.S. troops prepare to withdraw completely from Iraq in less than seven months, many question the ability of the nation's special forces in protecting Iraqis.
There are currently 46,000 U.S troops in Iraq, down from a peak of 170,000 during the height of sectarian violence in 2007.