SPIN BOLDAK, Afghanistan - A suicide bomber in a vehicle attacked a convoy carrying Afghan doctors working for the United Nations in southern Afghanistan, killing two doctors and their driver and wounding 15 others.
The Taliban claimed responsibility.
In other violence Sunday, seven children died after ordnance they were playing with exploded and militants ambushed and killed seven police, officials said.
The two doctors were under contract to the UN World Health Organization, combatting polio in Afghanistan, said Adrian Edwards, the chief UN spokesman in the country.
The driver also worked for the UN mission. All three were Afghan nationals, Edwards said.
The attack happened in the Spin Boldak district of Kandahar province as the convoy was on its way to vaccinate people, said provincial Police Chief Matiullah Khan.
The blast also wounded 15 other people, including 10 civilians and five Afghan guards protecting the convoy, Khan said. The bomber also died in the blast.
Khan said the doctors were travelling in clearly marked UN vehicles.
Edwards said the UN was trying to "determine if this was an explicit attack on the UN or if we were a target of opportunity."
"This attack was on innocent civilians working only for the people of Afghanistan, and is beyond comprehension," Kai Eide, the top UN official in Afghanistan, said in a statement.
UN Secretary General Ban Ki-moon condemned the attack "in the strongest possible terms."
Qari Yousuf Ahmadi, a Taliban spokesman, claimed responsibility for the attack, which he said targeted a UN mission convoy.
In comments posted on a website that has carried many previous Taliban statements, Ahmadi claimed two vehicles were destroyed and eight officials were killed.
Elsewhere, an explosion killed seven children and wounded 13 while they were playing with an old shell or other military ordnance, said Abdul Rahim Desewal, the district chief of Andar in Ghazni province.
Taliban militants ambushed a police patrol in central Afghanistan, killing at least seven officers, while U.S.-led coalition troops killed several militants in the east, officials said Sunday.
Authorities recovered the bodies of seven officers after Saturday's ambush in the central Ghazni province and another officer was missing, said Mohammad Sharif Kohistani, a provincial police official.
Lightly armed police officers often bear the brunt of Taliban attacks in Afghanistan. Over 900 officers were killed by insurgents in 2007.
More than 4,100 people, mostly militants, have died this year in insurgency-related violence in Afghanistan, figures compiled by The Associated Press indicate.
