SACRAMENTO, Calif. — Downtown Sacramento, where thousands reside and millions visit each year, has seen its share of live entertainment, tourists, buzzy nightlife, city employees — and violence. The shooting on K Street that killed six people, which authorities say stem from a gang dispute, is the worst shooting in the city’s history in terms of deaths and injuries. It’s not the only act of violence the city’s center has seen recently. In 2018, a shooting in a downtown parking garage near Seventh and K streets killed two men and wounded two others. The fatal incident happened in the early morn…