That's the number of people killed last year or approximatively 17 persons each day. That's just insane!
Obviously, gangs and drugs trafficking are present everywhere in Brazil or more generally in South America. And of course, these death squad killings are done presumably to help citizens but the main issue is that there is no arrest warrant of any kind. They base their moves on biased decisions. By example for every cop shot, at least 10 suspected gang members were killed.
The worst part is that you can be killed just because you're at the wrong place at the wrong time. In case of collateral damages you were probably a “suspected” drug dealer.
The jump from local heroes to contract killers is really thin. A lot of poor people and especially kids and teenagers abandonned in the streets with an ineffective system to provide a child welfare don't see other way to survive than to rob local stores. That brings a lot of boys being killed by gunmen employed by stores owner driven to desperation by robberies.
Some think “they are a force for good” because it may be the only way to clean up the streets and maybe that's presumably true until someone of your friends or family get shot by these militias…