Iraqi officials say two car bombs have killed at least eight people at crowded markets.
The first bomb exploded in a market in the northern city of Mosul, killing five people and wounding more than 20 others. Authorities believe the blast was aimed at a police patrol.
Hours later, a car bomb killed three and wounded 25 at a market south of Baghdad. That market was also attacked Sunday.
Separately, military officials say an American Marine was killed during combat operations in al-Anbar province.
Meanwhile, a previously unknown Shi'ite Muslim insurgent group says it is involved in attacks on American, British and other coalition forces across Iraq. The message from the "Muslim Resistance in Iraq" group claims its members are pledged not to target Iraqi soldiers and civilians.
A videotaped statement from the insurgents was broadcast Sunday by a Lebanese television station.