At least 14 people died in a weekend of violence in Rio de Janeiro, including two policemen who were killed when their helicopter was brought down by warring drug gangs. The violence came just two weeks after Rio de Janeiro was chosen to host the 2016 Olympic Games and highlights concerns over security in the city during the event.

Violence erupted between rival drug gangs in the early hours of Saturday when members of Rio’s biggest gang, the Comando Vermelho (CV, or Red Command), invaded a hilltop shantytown controlled by a rival gang, Amigos dos Amigos (ADA, or Friends of the Friends).