Manhunt after Silk Road attack

The European tourists were treated in hospital and released

ISLAMABAD, Pakistan (CNN) -- Pakistani police are investigating an apparent grenade attack on a tourist bus carrying at least 21 tourists most of them Europeans.

Twelve of the travellers -- including seven Germans and two Austrians -- and two Pakistanis were injured after an explosive device at their bus in Mensehra, 93 miles east of Peshawar.

The vehicle had stopped at an archeological site along the historical Silk Road when the attack happened on Saturday.

"All of a sudden we heard a very loud explosion and I saw only fire and some dust and some people shouting and crying," said Rita Mijailovic, a German tourist guide who was standing near the bus at the time of the attack.

" I saw blood and two people lying on the floor and I asked what happened. Nobody knew anything and then we went with three taxis to the hospital."

None of the injuries was serious and all of the victims were treated and released at a local hospital.

The German Embassy said it was aiding in the investigation. So far, Pakistani authorities said they have no suspects, although some people have been brought in for questioning.

The tourist group was taken back to Islamabad, where they stayed overnight on Saturday. The group was destined for China as part of a tour of the ancient Silk Road.

Pakistan's tourism industry has been hit since the September 11 attacks on the United States and a military standoff with neighbouring India in December. Many countries have advised their nationals to avoid travelling to Pakistan.

No one claimed responsibility for the attack -- the fifth such incident on Westerners in Pakistan this year.

In May, a bomb attack at the Sheraton hotel in Pakistan's main commercial city of Karachi killed 14 people, including 11 French engineers.

Last month 12 Pakistanis died and 20 were seriously injured in a bomb attack on the U.S. consulate in Karachi.

A verdict is due this week in the trial of four men over the kidnapping and murder of U.S. journalist Daniel Pearl who disappeared in Karachi in January researching a story about Pakistani militants.