"The Taliban forced villagers to stand around an area along a road in Kharkaran area of restive Chahar Dara district late Sunday, to cover themselves while planting a landmine. But the home-made device detonated accidently, causing the casualties," a resident told Xinhua by phone anonymously.
The militants tried to cover themselves among the civilians and avoid bombing from the government air-force, he said.
Inamuddin Rahmani, spokesman of the provincial police department, confirmed the incident, saying three militants have been killed by their own mine in the area, where 10 civilians have also been injured.
The wounded people have been rushed to a hospital by residents, said the source.
On Saturday, five militants, including a local Taliban leader, were killed in a government forces' offensive in Chahar Dara.
Fighting has escalated in Afghanistan as the Taliban insurgency spreads from its traditional strongholds in the south and east to the once peaceful region in the north, where Taliban have been recruiting from the youth.
XINHUA/MNA