On 16 March 1988 Stone staged a single-handed attack upon a collective Provisional IRA funeral which was being held at Milltown Cemetery in West Belfast for three IRA members shot dead ten days earlier by the British Army in a failed car bombing attack they had tried to stage in Gibraltar. As the coffins were being buried, Stone, who had entered the mourning crowd pretending to be a part of it, attacked the assembly with multiple RGD-5 grenades and gunfire from a semi-automatic pistol. He killed three people, including an acknowledged IRA member (Kevin Brady), and injured sixty others. After a subsequent foot chase through the cemetery grounds, with Stone throwing hand grenades and firing at a pursuing mob, he was caught and overpowered. He was beaten and there was an attempt to kidnap him using a car before the Royal Ulster Constabulary arrived on the scene and forced the crowd off of Stone (who was now semi-conscious from the beating he had sustained) and arrested him. He still walks with a slight limp as a result of his thigh bone being dislocated during the attack.