A policeman stands guard as people line up to vote at a polling station in the northern city of Katsina, April 21, 2007. Voting began in Nigeria's presidential election on Saturday hours after attackers tried to blow up the electoral headquarters, underlining fears that violence and abuse would mar the poll. The vote is intended to mark a democratic milestone for Africa, the first handover from one civilian president to another in the continent's most populous nation.
REUTERS/RADU SIGHETI