A fancy-dress sex party was is full swing at a Melbourne nightclub when police armed with semi-automatic rifles stormed in and shot a couple at close range, CCTV shows.
Victoria's anti-corruption watchdog is now overseeing the internal investigation into the shooting, which occurred in a nightclub that lodged a complaint against police only a week earlier.
The CCTV footage obtained by Fairfax Media and viewed online shows the heavily-armed Critical Response Team entering the Inflation nightclub shortly before 4am on Saturday.
They make their way through the nightclub before surrounding the man and woman in the back corner of a dimly-lit room.
A torch is shone on the couple, and then there's a flash as police fire - two punters walking by on an upper level cover their ears.
The entire process took 32 seconds.
A 35-year-old man dressed as the Joker was shot in the torso and a woman dressed as fictional supervillain Harley Quinn was shot in the leg.
The man remains in a stable condition in The Royal Melbourne Hospital and the woman was recently discharged from The Alfred.
But the grainy footage doesn't clearly show what the couple were doing ahead of shots being fired, including whether the man was brandishing a gun, as claimed by police.
Victoria's Independent Broad-based Anti-corruption Commission is now investigating the shooting.
"There will be from time to time incidents that need to be investigated thoroughly and that process should be allowed to run its course," Premier Daniel Andrews said on Tuesday.
The IBAC probe encompasses the evidence of nightclub staff and witnesses, initial police reports and available CCTV footage.
IBAC will also oversee Victoria Police's own internal investigation.
Inflation nightclub's owner Martha Tsamis said the man wasn't holding a gun but was in a "compromising position" with the woman when police "stormed in".
"Security verified that a plastic toy accessory was displayed to, and passed by security and this information was given to police on arrival," Ms Tsamis said in a statement last week.
"Police have over reacted to an anonymous phone call and ignored the advice of security."
Victoria Police said the man pulled out a handgun and wouldn't drop it before he was fired upon.
Inflation last week lodged a complaint against police over a drug search at the nightclub.
It has previously taken police to the Victorian Civil and Administrative Tribunal over a freedom of information dispute.