Two men try to extinguish a tire fire Thursday in Sitra, Bahrain, near the site of an opposition rally.Nightly clashes between riot police and protesters continued Thursday night nationwide. Hasan Jamali/AP hide caption

itoggle caption Hasan Jamali/AP

Black smoke billowed from burning tents in Pearl Square in Manama, Bahrain, earlier today (March 16, 2011). Joseph Eid/AFP/Getty Images hide caption

itoggle caption Joseph Eid/AFP/Getty Images