In Pakistan, at least four people have been killed and six others injured in a bomb blast in Swat valley. According to police sources, the explosion took place in a busy market situated near Sohrab Khan Chowk in Mongora city. Police said the bomb was planted in a plaza and several shops were destroyed by the impact of the blast. Police and other law enforcement agencies put a security cordon around the blast site . No group claimed responsibility for the attack.