A gang turf war broke out when 40 armed men invaded Rio de Janeiro's largest slum, killing at least six people as the city prepares for a Rolling Stones concert and Carnival, police told Reuters on Thursday. Police squads raided the area, not far from Rio's beaches and posh neighborhoods, after the clash erupted in Rocinha on Wednesday night. They arrested seven people but raids and shooting continued into the early hours on Thursday. A leader of a local drug gang and several more people were wounded. A 14-year-old was among the six dead. Police could not say whether those killed were drug traffickers or slum dwellers, who often die in the cross-fire. The invading gang, armed with assault rifles, machine guns and grenades, shot up power transformers in the slum, leaving it without light. Many slum dwellers could not get back to their homes after work due to the shootout. The confrontation was the first big incident in Rocinha this year but in 2005 and 2004 it suffered various flare-ups of violence in which more than two dozen people died. --More 23 06 Local Time 20 06 GMT