In mid-1920, republicans won control of most county councils, and British authority collapsed in most of the south and west, forcing the British government to introduce emergency powers. About 300 people had been killed by late 1920, but the conflict escalated in November. On Bloody Sunday in Dublin, 21 November 1920, fourteen British intelligence operatives were assassinated; then the RIC fired on the crowd at a Gaelic football match, killing fourteen civilians and wounding sixty-five. A week later, the IRA killed seventeen Auxiliaries in the Kilmichael Ambush in County Cork. In December, the British authorities declared martial law in much of southern Ireland, and the centre of Cork city was burnt out by British forces in reprisal for an ambush. Violence continued to escalate over the next seven months, when 1,000 people were killed and 4,500 republicans were interned. Much of the fighting took place in Munster (particularly County Cork), Dublin and Belfast, which together saw over 75 percent of the conflict deaths.