NATO forces confirmed Sunday's attack in the city of Gardez but did not have details. Spokesman Master Sgt. Jason Haag said only that there was "some sort of attack at Gardez."

A spokesman for the provincial government said the bomb went off in an area of the Afghan base where shopkeepers sell goods to both Afghan soldiers and their partnered NATO troops.

The spokesman, Rohullah Samon, said two shopkeepers were killed and at least 18 people were wounded, including three foreign soldiers.

Most of the NATO forces in Gardez are American.