Iraqi officials say a wave of bombings has hit the capital and cities in the north, killing at least 18 people and wounding more than 30 others.

Authorities said many of the attacks Thursday – a mix of car bombs and roadside bombs – appeared to target security forces.

In Baghdad, multiple blasts killed at least eight people, while bombings in Kirkuk killed another nine people.

A suicide bomber also struck in Baquba, north of Baghdad, and explosions hit the cities of Samarra and Taji.

There was no immediate claim of responsibility for the bombings, which broke a period of relative quiet in Iraq.

Sunni Muslim extremists are blamed for most attacks in Shi'ite-majority Iraq.

Near simultaneous suicide attacks and car bombings in eight cities last month killed at least 46 people and wounded more than 200 others. Those attacks came days before Baghdad hosted an Arab League summit.