A suicide bombing targeting a Shiite Muslim procession in Pakistan's largest city of Karachi killed 30 people and wounded dozens more yesterday, as Shiites across the country marked the key holy day of Ashoura. Outraged Shiites responded by setting fire to buildings and vehicles at the blast site and hurling stones at security forces had been guarding the march for their failure to prevent the attack. Authorities responded by firing into the air. The bombing was the latest in a wave of violence to hit Pakistan since the army started taking on Islamist militants allied with al-Qaida and the Taliban, with terrorist strikes killing 500 people since October.