Police said the incident occurred on Sunday morning at around 3:20 a.m. local time (1720 UTC Saturday) at the Love Machine club in the southeastern suburb of Prahran.
Osmani was rushed to a hospital in a critical condition.
It's understood at least one man, believed to be a security guard, was shot in the face.
Links to an outlaw motorcycle gang are being investigated by detectives who believe the gang has made extortion attempts on the nightclub, the publication said.
"This is just a horrendous act". A busy nightclub, one of the main nightclubs in one of the main entertainment precincts of Melbourne. The victims suffered "horrific injuries" from a weapon fired in close proximity, he added.
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It would also be helpful for people to recall and write down everything they consumed the week before getting sick. No common brand or supplier of the tainted meat has been identified yet, and the investigation is ongoing.
"An investigation is underway and the exact circumstances are still being established", a police spokesman said in a statement.
The police told a televised news conference there was no suggestion yet that the shooting was terror-related.
Prahran shooting update: two people in critical conditions in the Alfred Hospital, a third is in a stable condition.
Police say two men, aged 29 and 50, were hospitalised with non-life threatening injuries in the shooting at Love Machine.
A 26-year-old man also took himself to hospital on Sunday afternoon with injuries stemming from the shooting but they were not life-threatening.
Chapel Street is home to a number of popular nightclubs and the shooting on Sunday occurred while many people were still out. "I love you bro", posted a friend.