The bomb, hidden on a bicycle, exploded as farmers gathered in Darzab district of the province of Jawzjan on market day, but there was no immediate word on who was responsible, Reuters reported.
"People usually come from surrounding villages on Monday to do their shopping in the city," said Reza Ghafoori, a spokesman for the provincial governor.
"Enemies of the people of Afghanistan put an improvised explosive device on a bicycle and targeted our innocent countrymen who were there to buy their needs."