The blast, which also wounded 17, struck in the Wasati neighbourhood in southern Kirkuk, a tinderbox city that is at the centre of a long-running territorial dispute between the central government and Iraq's autonomous Kurdish region.
The evening explosion came amid a protracted surge in bloodshed that has left more than 3,700 people dead so far this year, fuelling fears Iraq is slipping back into the all-out conflict that plagued it in 2006 and 2007.
Violence has surged in the past year to its highest level since 2008, while anti-government fighters also control an entire city a short drive from Baghdad and parts of another.