This weekend, a fierce gun battle between two drug gangs in Rio de Janeiro’s “Monkey Hill” slum left some ten suspected gang members dead and entire neighborhoods fearing for their lives as the sound of automatic fire could be heard all day long. At one point, a police helicopter, loitering over the area to direct anti-gang police measures, was hit by gunfire, caught fire and crashed, killing two police on board and injuring several others.

The drug violence of Rio’s favelas is nothing new. But the helicopter shoot-down was shocking, just as it was to hear of such incredible violence in a city that just a month before had been tapped over contenders such as Chicago and Tokyo to host the 2016 Summer Olympics.

In light of the recent gun battle, Brazilian officials have sent thousands of extra police into the slum to crack down on the violence and lawlessness there, but clearly, they face an uphill struggle. Even though the Olympics are several years away, the level of the security problem in the city will surely cast as much of a shadow over the coming games as terrorism fears did over the 2004 Olympics in Athens. At the moment, the U.S. State Department notes that Rio is a fairly dangerous city, crimewise, and that all of Brazil has a crime rate that is quadruple that of the United States. The Overseas Security Advisory Council echoes the State Department’s assessment of things, noting that the “Government of Brazil (GoB) is locked in an intense struggle against drug gangs for control of large areas of the Rio de Janeiro metropolitan area.” After this weekend’s carnage, even that assessment seems to be putting things mildly.

Hopefully, Brazil can marshall the resources and the will needed to address the security problem in a permanent fashion, rather than temporarily suppressing it or displacing it elsewhere. The Olympics have a nasty habit of costing its host cities far more in the long run than they bring in, revenue-wise. After this weekend’s Monkey Hill bloodbath, it might be tempting to wonder if money spent on stadiums and athlete villages should be first spent on keeping the poor sections of town free of machinegun fire.