An explosion outside a base of a US security firm on Saturday killed at least 12 people in Afghanistan's southern province of Kandahar, witnesses said.
Violence has surged in the past 19 months in Afghanistan, the bloodiest period since US-led troops overthrew Taliban's government in 2001.
The blast happened close to a highway in the western outskirts of Kandahar city, they said. Some witnesses suspected the blast was caused by a suicide car bomber and was aimed at a US security firm called USPI.
A police vehicle and a passenger car were also hit by the explosion, witnesses said, adding three police were also amongst the victims.
"We saw 12 dead bodies being dragged away. They were civilians and also Afghan employees of the company," said one witness who refused to give his name.
A Reuters reporter saw 15 bodies in the morgue of a hospital in Kandahar city. They included five police, three women and a child, he said, adding 18 more people were wounded in the blast.
The blast came a day after a suicide bomber inside the city killed a district chief and three of his children at the gate of their home. There was no immediate claim of responsibility for Saturday's attack.
The Taliban movement has taken credit for many of the suicide attacks in the past.
The group largely relies on suicide raids and roadside bombs as part of its campaign against the Afghan government and Western troops based in the country.
Some 7,000 people have been killed in the past 19 months in Afghanistan by violence which is rising despite the presence of some 50,000 Western troops led by NATO and the US-led coalition as well as more than 100,000 Afghan forces.
The violence has hardly hit southern and eastern areas where the Taliban and their allies such as Al- Qaeda are mostly active.
It has hampered reconstruction projects in the war-torn country and forced dozens of aid groups to halt their activities.