Voters are held back by security personnel as they await the opening of a polling station in Harare March 29, 2008. Zimbabweans began voting on Saturday in the most crucial election since independence from Britain in 1980, with veteran President Robert Mugabe facing the biggest challenge of his 28-year-rule. The house of a Zimbabwean ruling party parliamentary candidate was bombed early on Saturday in the first violence in the country's election, police said. REUTERS/Mike Hutchings (ZIMBABWE)