TEHRAN, Young Journalists Club (YJC) - The blast, near one of the city's main markets, sent a huge cloud of dust and smoke into the air.
Nematullah Barak, head of Mirwais hospital in Kandahar, said six dead and more 30 wounded, including several children, had been brought in.
A statement from the NDS intelligence service said the minibus, packed with explosives, was discovered in a large open yard of mechanics workshops but blew up before it could be defused.
There was no immediate claim of responsibility.
Hundreds of people have been killed or wounded in high-profile bomb attacks since the beginning of the year, many in the capital Kabul, but provincial cities have also been hit as the Taliban.
Tuesday's explosion came as the Taliban pushed ahead with their spring offensive, launched last month, with fighting in other areas of the country.
Source: Reuters