Taliban claims responsibility for suicide bombing near UN offices in the southern Afghanistan city.
A blast has killed a district police chief and six others in Kandahar province near a guest house of the United Nations refugee agency and the office of International Relief and Development, authorities say.
The deaths, which included three Afghan UNHCR workers, occurred on Monday morning when a suicide bomber drove an explosives-laden vehicle into a checkpoint in an area of Kandahar city that houses several international NGOs and guest houses.
The Taliban claimed responsibility for the attack, with Qari Youssef, the anti-government group's spokesman, saying the UN guest house was the assailants' target.
The provincial governor's office said a gunfight between security forces and attackers erupted after the explosion.
The battle lasted for seven hours before the fighters were shot dead, according to the office of the Kandahar governor.
An Associated Press video showed footage of the UNHCR building, 480 kilometres south of Kabul, after sustaining damage from the explosion. The building, on a street street strewn with rubble following the attack, had large chunks of its outer walls and windows blown out. Two other Afghan workers at the UN's refugee agency were wounded in the attack.
"I saw from the window that a thick smoke with fire was rising from the IRD office. Then police arrived and blocked the area because firing was going on," Abdul Nahim, a local resident describing the scene from his windows, blasted out from the attack, told Reuters news agency.
Al Jazeera's Bernard Smith, reporting from Kabul, said the Kandahar district police chief was killed in one of the safest parts of Afghanistan's second largest city.
The Kandahar attack, which came on a day President Hamid Karzai was travelling to a regional security summit in Turkey, was yet another sign of changing Taliban tactics, our correspondent said.
There are now carrying out "more focused attacks on significant sites," he said.
United Nations Secretary-General, Ban-Ki Moon began his New York press conference on Monday by addressing the attack.
Ban said the attack, like others before it, "underscores the risks that UN and international aid workers face in Afghanistan," but that he "would like to emphasize once [again] this work is purely humanitarian, its sole purpose is to improve the daily lives of the country's people. Our thoughts this morning are with the victims and their families."
The Secretary-General's statement came after a similar condemnation and a call for Afghan government to bring those responsible to justice by the Security Council.
Current Security Council President, Nigerian Ambassador Joy Ogwu, said the membership of the UNSC condemned the attack "in the strongest terms" and called on the government of President Hamid Karzai to bring those responsible to justice.