A bomb blast in a market in the northwest tribal region of Pakistan killed 21 people and wounded at least 50 on Saturday, according to officials. Shahid Khan, an assistant tribal administrator, said the explosion took place when the market in Parachinar was crowded with retailers buying fruit and vegetables from a wholesale shop. Lashkar-e-Jhangvi, a banned sectarian militant group that has attacked minority Shiite Muslims in the past, claimed responsibility for the attack.