May 1, 2012 (29 images)

Police make an arrest and throw tear gas to move the crowd back during a May Day protest in Oakland, California on May 1, 2012. UPI/Terry Schmitt

New Jersey Devils David Clarkson celebrates the Devils 3rd goal by climbing on top of the Philadelphia Flyers net in the third period at the Wells Fargo Center in Philadelphia on May 1, 2012. At right is Philadelphia goalie Ilya Bryzgalov. New Jersey defeated Philadelphia 4-1. UPI/John Anderson

An Oakland police officer is kicked in the shoulder as he wrestles a demonstrator to the ground during a May Day protest in Oakland, California on May 1, 2012. Demonstrators closed streets and clashed with police. UPI/Terry Schmitt

Atlanta Hawks guard Kirk Hinrich (6) goes over Boston Celtics forward Paul Pierce (34) in the first half of game 2 of the first round of the Eastern Conference Playoffs at Philips Arena in Atlanta on May 1, 2012. UPI/David Tulis