This undated photo made at a unknown location shows 15-year-old Alexandros Grigoropoulos. Some of the worst riots Greece has seen in years began within hours of the fatal shooting of Alexandros Grigoropoulos on Saturday night in the central Athens district of Exarchia. The circumstances surrounding the shooting of the teenager Grigoropoulos are still unclear. Two policemen claimed they had come under attack by a group of about 30 youths, and that three warning shots and a stun grenade were fired when they sought out the group a few minutes later. But witnesses have disputed the officers' accounts, telling Greek media that the police intended to shoot the youths. One officer has been charged with murder and the other as an accomplice.