Editor’s note: Some images in this gallery may be disturbing because of their violent or graphic nature.

Photographer Felipe Dana was born and raised in Rio de Janeiro, so he is no stranger to the city’s violence. But his job as a journalist has given him insight into the violent world of Brazil’s favelas that most ordinary citizens are immune to.

At around the same time that Dana started working as a photojournalist for the Associated Press, the police began a pacification program meant to help curb violence in the favelas. That was in 2009, and Dana says that at first he was optimistic about the program. Indeed, in the early stages of the program, it seemed to be working, and Dana was able to go into areas he never would have been able to go without securing permission from the controlling gangs. But the improvements were only temporary. The program expanded quickly, and soon the police didn’t have enough manpower to maintain control. Instead, Dana thinks the situation has gotten worse: “It used to be that you at least knew who was in charge of a certain patch of turf. Now, even in slums where the police are still present, they aren’t really in control. Now the drug dealers are again in plain sight. Teenagers openly toting assault weapons are a common sight, and you don’t know when someone might open fire.”

That said, Dana doesn’t believe that the upcoming Olympic Games are going to be adversely affected by the brutality of life in Rio’s favelas. He thinks that the increase in security will keep foreign visitors safe. “Traffickers told me they won’t be looking for conflict,” he said. “They said they would lay low unless police invade their areas. It’s a bad time to pick a fight, and they are aware of that. So unless something extraordinary happens, violence shouldn’t be a big problem during the Games.” However, Dana says the real tragedy is that once the Olympics are over, the favelas won’t have changed at all and once the increased security measures are gone, “people will again find themselves caught in the crossfire.”