Witnesses said a police cordon was set up after the incident near Silver Street on Saturday night, May 4.
It is believed a man suffered injuries and was treated by paramedics at the scene before being taken to hospital.
Back Broad Street, which runs off Silver Street between bars Society and Hops, remained cordoned off by police on Sunday morning.
The scene where the cordon was in place
A worker at a nearby takeaway said: “All I know is the police were there the next morning when I got into work, at around 10am.
“Police had cordoned off the little alleyway between Society and Hops and there were two police officers stood there.”
Greater Manchester Police and North West Ambulance Service have been approached for comment.
This comes after multiple violent incidents in the area in recent years.
35-year-old Piotr Ludwiczak died in hospital on July 8 last year after an incident outside a Silver Street bar.
Two men were arrested.
A father was also stabbed trying to protect his son who was “set upon by a gang” outside Hidden Bar on the same street in 2022.
Two police officers were attacked on the street last August after a fight broke out, with two people later being arrested.
And in nearby Market Street, 18-year-old Abdikarim Abdalla Ahmed was stabbed to death in March 2022.
Abdikarim – known as Abdi to friends and family – was described by his mother as “a loving, caring person who helped and looked after his family from a young age”.