ABSTRACT THREE-YEAR-OLD Quiona Simmons gets to play in the front yard of her South Central Los Angeles home now.A virtual end to what were almost daily shootings is an unexpected benefit in the aftermath of the unrest here in what was the epicenter of the worst riots in this country this century (JAMA. 1992;267:3001-3002).Before, says Quiona's mother, Kecia Simmons, it was like being in a military zone, where the all-too-common sound of gunshots sent her scrambling to make sure her children were in the house or enclosed backyard. Now it's quiet, peaceful. I don't mind them playing outside now. You can take a walk, water your grass. You don't have to worry about anything.A truce between the area's two main gangs, the Crips and the Bloods, is apparently responsible for the night-and-day difference. In some neighborhoods, walls that were mosaics of graffiti have been freshly painted by gang