On 8 December 1987 at around 4:20 p.m., Vitkovic entered the building at 191 Queen Street, Melbourne, carrying a sawn-off M1 carbine in a brown paper bag. Vitkovic went to the 5th floor office of the Telecom Employees Credit Co-operative where a former friend (and the primary target), Con Margelis, worked. Margelis was called to the counter and briefly spoke with Vitkovic, who then pulled his weapon from the bag. The weapon jammed and Margelis ducked behind a counter; Vitkovic then began firing, killing a young female office worker, Judith Morris. A robbery alarm was activated by a staff member at 4:22 p.m. Margelis escaped the office unharmed, and hid in the women's toilets. Vitkovic took an elevator to the 12th floor, to the Australia Post philately security section. There, Vitkovic shot and injured a man and a woman, then pointed his gun at a woman sitting at her desk, only to pan his aim to the left and shoot Julie McBean and Nancy Avignone dead. A man in the corner office on that level, Warren Spencer, was also killed.