KANDAHAR, Afghanistan — A suicide bomber blew himself up near a police vehicle Friday in volatile southern Afghanistan, killing three policemen and a civilian, a police official said.

The attack happened on the outskirts of Lashkar Gah, the capital of Helmand province. Eight people were wounded, including a policeman and seven civilians, said provincial police chief Mohammad Hussein Andiwal.

Helmand is the biggest opium poppy-producing region in the world and has seen some of the heaviest fighting between international troops and insurgents.

In eastern Kunar province, a truck supplying fuel to NATO troops hit a roadside bomb that killed the Afghan driver Thursday, said a statement from NATO's International Security Assistance Force. No NATO service members were hurt in the attack.