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KARACHI, Pakistan (AP) — A police officer says a bomb has exploded outside a Shiite Muslim mosque in Pakistan’s largest city, killing at least two people.

Azhar Iqbal says the bomb was planted on a motorcycle outside the mosque in the eastern part of Karachi. At least 10 people were injured by the explosion.

The attack came as Shiites were celebrating the holy month of Muharram.

Pakistan has a long history of sectarian violence by extremist Sunni and Shiite Muslims in Karachi and other parts of the country.

The Sunni-Shiite schism over the true heir to Islam’s Prophet Muhammad dates back to the seventh century.