Description:A car bomb exploded on Sunday near a convoy of buses taking Pakistani Shi'ite pilgrims to Iran, killing at least 20 people and wounding 24, officials said, the latest attack on the minority sect. Witnesses said the blast occurred as the three buses were overtaking a car about 60 km (35 miles) near the Iranian border west of Quetta, capital of sparsely populated Baluchistan province, site of many sectarian attacks.(0:38)