Pakistan's largest city, Karachi, shut down Monday to mourn the 45 people killed in a car bomb explosion outside a mosque that also wounded about 150 others.
Police say the bomb exploded Sunday as worshippers were leaving evening prayers in a neighborhood dominated by minority Shi'ite Muslims. Several buildings caught fire and people were trapped under the rubble of structures that collapsed. Women and children are among those wounded.
Paramilitary officer Pervez Ahmad says a chemical used in the blast caught fire and spread the destruction.
No one has claimed responsibility, but Sunni Muslim militants with links to al-Qaida and the Taliban frequently target their Shi'ite neighbors across Pakistan, especially in Karachi.
According to the independent Human Rights Commission of Pakistan, at least 2,284 people died in ethnic, sectarian and political violence last year in Karachi.