Brig. Gen. Sarhad Qadir said Saturday morning that the parked cars exploded over a 30-minute period in three adjacent Kurdish areas.

Qadir said it was not known whether there was a specific target for the blasts.

Kirkuk is 290 km north of Baghdad and is home to a mix of Arabs, Kurds and Turkomen, who all have competing claims to the oil-rich area.

The Kurds are seeking to incorporate Kirkuk into their autonomous region in Iraq's north. Arabs and Turkomen oppose that effort.