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In pictures: Karachi bomb blast

Pakistani residents gather after the bomb blast in Karachi on March 3, 2013. A bomb attack in Pakistan's largest city Karachi on Sunday killed at least 23 people, including women and children, and wounded 50 others, police said. AFP PHOTO/Asif HASSAN

In pictures: Karachi bomb blast

A suspected suicide bomber attacked Shi'ite Muslims as they were leaving a mosque in Pakistan's commercial capital on Sunday, killing at least 45 people, in another signal Sunni militants are escalating sectarian attacks.