A man lights his pipe at the 4/20 pro-marijuana rally in Civic Center Park in downtown Denver April 20, 2013. Thousands of marijuana enthusiasts gathered for an annual weekend celebration of cannabis, the first such assemblage since Colorado voters legalized the recreational use of pot last fall. Two people were shot at the rally, police said. One person was shot in the leg and another was "also down with unknown injuries," Denver police said on their Twitter page. REUTERS/Rick Wilking (UNITED STATES - Tags: DRUGS SOCIETY POLITICS CIVIL UNREST HEALTH)