Police say a powerful roadside bomb has exploded in southern Afghanistan, killing at least 12 civilians.

Nabi Jan Mullahkhail, Helmand province's police chief, says the bomb exploded Saturday afternoon. He said at least 12 bodies have been brought to a local hospital, while the blast wounded eight people.

A relative of those killed in the blast says the death toll may be even higher.

No one immediately claimed responsibility for the blast. The Taliban plant roadside bombs to target Afghan security forces, though the bombs often explode as civilian vehicles pass by, killing them instead.