The first details around the blast of chaos and violence that struck Melbourne’s CBD on Friday evening have emerged, with the police arguing the shooting of a man armed with a broken bottle was justified given the threat he posed to officers.

Victorian Police Transit and Public Safety Command Assistant Commissioner Dean McWhirter, speaking on Saturday afternoon, said two separate incidents merged around Princes Bridge near Flinders St Station, with the chaos kicking off about 5.30pm.

At that time, a male on a tram allegedly attempted to rob a man and a woman before exiting at the landmark CBD bridge.

The South Melbourne man, 27, allegedly attacked four people with a bottle after leaving the tram, a 67-year-old Warneet man, a 56-year-old Collingwood woman, a 24-year-old Kennington woman and a 46-year-old Hoppers Crossing woman, putting all four in hospital with injuries including lacerations and bruising.

The police and protective service officers arrested the man and established a crime scene, Assistant Commissioner McWhirter said, before a second alleged offender, a 20-year-old Pakenham man, approached a PSO around 7pm.

The young man allegedly told the officer he was going to “harm him” and the officer alerted a fellow PSO to the threat.

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