The worst conflagration and paroxysms of violence occurred during the Bosnian War (1992-1995) which was essentially a civil war in Bosnia-Herzegovina between Bosnian Serbs (supplied and aided by Serbia) and Bosnian Muslims and Bosnian Croats. It would become a complicated war, however, as Croats and Serbs would once in a while team up together against the Muslims. In the course of this war about 100,000 people died. The cosmopolitan city of Sarajevo, an erstwhile model of ethnic multiculturalism, descended into a scarred battlefield with snipers lurking behind every building and Serb artillery units from the surrounding hills bombing people lined up at grocery stores. The war was not merely a contest between combatant forces on the battlefield, but also an effort to "cleanse" towns and cities. Serbian death squads roamed the streets, murdering and torturing civilians at whim. The worst episode of mass murder occurred in Srebrenica where Bosnian Serb forces rounded up thousands of Muslim males and systematically massacred them while the international community looked on. Finally, the United States had to step in in 1995 to end the conflict. In the late Nineties another crisis erupted in Kosovo, a province of Serbia, when Serbian death squads started killing Muslim citizens. Only NATO bombing stopped the massacres.