A man has been rushed to hospital in a critical condition after a fight on the footpath in the Brisbane CBD.

Emergency services were called to digiDirectBrisbane on Adelaide Street about 10.45am on Monday after reports of a fight outside the camera store.

Police cordon off the scene as detectives make their way there.

A man was taken to the Royal Brisbane and Women's Hospital and paramedics described the patient as suffering from "a medical episode".

Witness Ashley Nguyen, from nearby restaurant Banh Mi Now, described it as "like a drunken fight".