<br/>At least ten persons were killed and 20 others injured today when a powerful bomb went off in a crowded market in Pakistan's restive Khyber tribal region. The bomb was planted at a shop in the weekly market at Meherban Kalay village in Khyber Agency. <br/><br/>The injured were rushed to the hospital and the security forces cordoned off the area. Pak Prime Minister Yousuf Raza Gilani has condemned the blast and asked authorities to inquire into the incident.