The attack happened Friday afternoon as a pickup truck carrying villagers to a nearby bazaar rolled over the bomb, detonating it in the Khan Neshin district of Helmand province, said Daoud Ahmadi, spokesman for the provincial governor.

"It was a very heavy explosion, the vehicle was destroyed," Ahmadi told The Associated Press by telephone from Lashkar Gah, the capital of Helmand province. Ahmadi said all the victims were men.

Calls to the area where the explosion happened did not go through Saturday.

The governor's office in Helmand province released a statement blaming the attack on "the enemy of people and the country."

NATO forces have poured troops into the southern provinces of Helmand and Kandahar, making some progress in routing the Taliban. But fighting and insurgent attacks have continued.

Also Saturday, a suicide bomber blew up a stolen police car that had been packed with explosives, injuring at least 14 people near an army checkpoint in northern Afghanistan.

Muhbobullah Sayedi, the spokesman for the governor of Kunduz province, said the force of the blast Saturday morning destroyed several nearby homes. The only person killed was the suicide bomber.

Five Afghan soldiers and nine civilians were injured.

Several of the civilians were in their homes at the time of the blast, Sayedi said.

The attack happened in Chahar Dara district, the most volatile district in the northern region.