Protesters and anti-riot troops clash in Machdallah, Bouira Province, Algeria, on April 17, 2014. Several injuries were reported during Thursday's clash. Some polling stations were vandalized by demonstrators. Polling stations opened on Thursday in Algeria, as some 23 million registered voters cast their ballots to elect their next president in the North African nation's fifth presidential election since the adoption of the plural party system in 1989. (Xinhua/Mohamed Kadri)