Three separate blasts in the southern Afghan city of Kandahar killed at least 12 people and wounded more than 30 others Tuesday.

Local officials said that in the first attack, a suicide bomber on a motorcycle blew himself up near a police checkpoint in downtown Kandahar, killing at least four children and a police officer and wounding 16 others.

Hours later, two bomb blasts near Kandahar's busy market killed three policemen and at least four civilians, and wounded more than a dozen others.

Local officials said the first explosion was relatively small, and as soon as police rushed to help the victims, a suicide bomber blew himself up near the gathered police and onlookers.

No one has claimed responsibility for the attacks.

Also Tuesday, NATO said one of its service members was killed by a roadside bomb in southern Afghanistan, though it provided no other details.