An investigation is underway after a man was knocked unconscious after being punched outside the Mexican Cafe.
The serious assault, which was captured on video, happened following a verbal altercation between a group of men, believed to be cafe security guards, and a member of the public.
The 30-second video shows the man moving towards the security guards before being punched in the face and falling backwards onto the footpath.
It is unclear what happened in the minutes before or after the incident.
Mexican Cafe general manager Matthieu Ferragati said the incident was terrible and that the cafe has since replaced its security company.
"I do feel terrible for the victim and I hope something like this will never happen again."
Ferragati said he spoke to the victim, who was "okay".
"The owner [of the Mexican Cafe] is totally shocked. We've been here since 1983, it's almost 38 years, this is the first time [we've] seen something like this."
He said the business runs famous Friday night salsa parties and wants to ensure people feel safe attending them.
Auckland City Police detective senior sergeant Steve Anderson said a serious assault happened in the early hours of Saturday, February 27.
Police are working to identify and locate the person responsible, including speaking to witnesses and reviewing CCTV footage, he said.
"Police are asking anyone with information about the incident, or who knows who may be involved, to contact us on 105 quoting file number 210227/7884. You can also contact Crimestoppers anonymously on 0800 555 111."
St John said it was called to Victoria St West at 1.41am on February 27.
One ambulance crew was sent to treat a patient in moderate condition who was transported to Auckland City Hospital.