5 killed in blast in Pakistan From Nasir Habib, CNN February 17, 2012 -- Updated 0954 GMT (1754 HKT) Authorities are trying to determine what caused the blast Explosion occurs in a market Islamabad, Pakistan (CNN) -- An explosion killed five people and injured several others in Pakistan's tribal region on Friday, a senior government official told CNN. Authorities were still trying to determine what caused the explosion, said Shahab Ali Shah, the top government official of Kurrum Agency, one of the seven districts of Pakistan's volatile tribal region bordering Afghanistan. The incident took place in a market of Parachinar, a town in Kurrum Agency, where people are gathered after their Friday prayer, Shah said.