Afghanistan ? A suicide bomber on foot detonated himself in a crowded market in eastern Afghanistan on Sunday just after a U.S. convoy drove by, killing at least 14 people and wounding 31, officials and witnesses said.

The attack in the city of Gardez damaged around 30 shops, shattered windows and destroyed the stores closest to the explosion. Three vehicles were damaged, including a taxi blasted by dozens of pieces of shrapnel.

Witnesses said a U.S. convoy appeared to be the target, and Maj. William Mitchell, a spokesman for NATO’s International Security Assistance Force, said there were initial reports of injuries to ISAF soldiers, though he didn’t have further details.

Six people died at the scene of the blast, police said. Another eight later died at a hospital, said Ghulam Hazrat Majedi, the doctor in charge of the Gardez hospital. He said two of the 31 people injured were in a critical condition.