KANDAHAR, Afghanistan -- A gunman opened fire Wednesday on a group of U.S. troops shopping on a busy street in this former Taliban stronghold, wounding one American and an Afghan before escaping, the U.S. military and witnesses said.

Afghan officials blamed the shooting on Taliban or al-Qaida fugitives and said they feared more attacks. The shooting occurred one day before Afghanistan's former king was expected to return to the capital, Kabul, after 29 years exiled in Rome. Mohammad Zaher Shah was to have come home last month, but his trip was postponed because of fears for his safety.

Witnesses said the Americans, who were wearing civilian clothes, were at a gun shop when the shots were fired. The Americans thought a firecracker had exploded until they noticed one of their group was bleeding, said Maj. Ralph Mills, a spokesman for U.S. Central Command in Tampa, Fla.

In stable condition

The wounded American, whose name was not released, walked to his vehicle unassisted, witnesses said. He was taken to the U.S. military hospital at Kandahar airport, where he was reported in stable condition.

The gun shop owner, who gave his name only as Daood, said one Afghan also was wounded. Another gunsmith, Mohammed Saleem, said the Americans left the scene quickly after the attack. He praised them for not opening fire on a street filled with children who had just left school for the day.

Afghan troops cordoned off the area and searched for the assailant. They also warned shopkeepers to be vigilant for further attacks.