Fifteen people, including four workers of United States Agency for International Development, were killed and number of others injured in a bomb blast at Lower Dir in Pakistan's Frontier Province on Wednesday.

The USAID workers were on a visit to a girls' school in the Koto area, located some 15 km from Lower Dir's headquarters in Timargarah, when the remote-detonated bomb went off. More than 70 persons have been injured in the blast.

A military source told rediff.com on conditions of anonymity: "Among those killed are four foreigners and one of their security guards. Some Pakistani security personnel have also been killed in the attack." 

Another military official said, "The bodies of the slain USAID workers and military personnel have been taken to the nearby army garrison."

When contacted by rediff.com, Wakil Muhammad, a medical officer at District Headquarters hospital in Timargarah, said: "So far, some 59

people have been rushed to the hospital. Four girl students have been pronounced dead, 10 are critically injured while 45 others have received minor injuries."

The slain girls were in their classroom when the bomb was detonated. So it is believed that the toll could go higher.

Sheer Bahadar, a local tribesman, said: "I saw three mutilated bodies of girls being taken back to their homes."

Local journalist, Amjad Ali Shah is also among the injured. His uncle, Azam khan told rediff.com, "I am going to see my nephew. He has been taken to Timargarah hospital. My relatives at the hospital have informed me that he is out of danger."