An article from 'Open Security' which covers more than El Salvador, notably Mexico and looks at the low profile, tentative success of the state talking to gangs - with the key features being better conditions for those in jail (as in Spain, Italy and the UK IIRC) and a wise retired soldier.

It opens with:
Talk of a pact with criminals is beyond the pale in Mexico’s presidential election campaign. But the tentative success of a deal with gang leaders in one of Central America’s most violent countries suggests the time may have come to explore a new style of negotiations aimed at reducing appalling levels of violence.

A month later, for the first time in years, the country recorded a day without a violent death; the official hope is now that the murder rate will fall in 2012 by 50 percent. The gangs have even agreed to halt forced recruitment of young people.
Citing Interior Minister David Munguía Payés, a retired general:
My hope is that they [the gangs] don’t commit serious crimes, like they are committing at the moment, because in reality the gangs aren’t going to disappear in the next 15 or 20 years. You will die, I will die, and still there will be gangs here in El Salvador. At best they just won’t be as violent as they are now.
Link:http://www.opendemocracy.net/ivan-br...als-with-devil

Brave men, maybe women too, on both sides to do this. Less violence is essential for public safety and civic life.