A Suicide car blast near UNHCR building in Kandahar

Three Afghan civilians were killed in a suicide attack in the southern Afghan city of Kandahar early on today, authorities in Kandahar said.

The blast was close to the Office of the United Nations High Commissioner for Refugees (UNHCR) building in Kandahar, the UN said.

"We are aware of an explosion which took place earlier this morning in the vicinity of the UNHCR guest house," United Nations spokesman Dan McNorton said. "All our international staff are accounted for ... the incident is still ongoing. We are working through our processes to make sure all our Afghan staff are safe."

Authorities in Kandahar said three civilians had been killed, describing the incident as a suicide attack.

"(There have been) three local civilians killed and another one wounded. A Nepali is wounded too," the provincial governor's media office said on its Twitter feed, adding that two armed attackers were still shooting at security forces.

The attack is the latest in a string of lethal assaults on foreigners in Afghanistan.

On Saturday, a suicide car bomber killed 13 troops and civilian employees of the NATO-led International Security Assistance Force (ISAF) in Kabul, including Americans, Britons and a Canadian, in the deadliest single ground attack against the coalition in 10 years of war in Afghanistan.