Updated

Afghan police say 18 civilians, including children, died when their minibus ran over a roadside bomb in southern Helmand province.

Deputy provincial chief Kamaluddin Sherzai says the explosion took place Friday morning in Nahri Sarraj district.

He says insurgents fired at police who responded to the explosion but that there were no casualties among the policemen.

However, Sherzai says three Afghan policemen died in a fight with insurgents Thursday night in Helmand's Gereshk district.

U.N.'s midyear report says the number of Afghan civilians killed in war-related violence has risen by 15 percent in the first half of 2011. Roadside bomb explosions were to blame for at last 440 of the 1,462 civilian deaths by violence.