Article published on the 2009-09-29 Latest update 2009-09-29 10:29 TU
The dead include ten children and seven women, according to the Interior Minstry.
Kandahar is a Taliban stronghold and has seen some of the worst violence in the Islamists' battle against western troops and the foreign-backed Afghan government.
Afghan and international troops arrived at the scene of the explosion, around 40 kilometres west of Kandahar city, the regional capital, and ferried the wounded to military bases for treatment.
On Sunday, three civilians, including a woman were killed when their car hit a bomb in the road in the same area.
Western governments have highlighted improvised explosive devices as the biggest challenge facing troops deployed to Taliban hotspots. Experts say they are cheap, are rigged to timers or remote controls, and can be linked into a chain of bombs to cause maximum damage.
Afghan President Hamid Karzai, beleaguered by accusations of fraud in last month's presidential election, has said he will launch peace talks with Taliban leaders if he wins another five years.