People watch as smoke rises from the police headquarters after it was hit by a blast in Nigeria’s northern city of Kano January 20, 2012. At least six people were killed in a string of bomb blasts on Friday in Nigeria’s second city Kano and the authorities imposed a curfew across the city, which has been plagued by an insurgency led by the Islamist sect Boko Haram. There was no immediate claim of responsibility for the apparently coordinated attacks. REUTERS/Stringer (NIGERIA – Tags: CRIME LAW CIVIL UNREST)