A witness told NZME they saw a man run into St Kevins Arcade on Karangahape Rd, assault someone attending a Monday night charity meal, then run towards Mercury Lane.
A resident, whose apartment overlooks Mercury Lane, said the street remained taped off at both entrances hours after the incident.
She said she had earlier seen detectives photographing the scene.
The resident, a university student who has lived in the area for 10 months, said she could see an open first aid kit, what appeared to be a bloodstained tissue, blue medical gloves and an item of clothing on the footpath.
She added a police helicopter and dog squad had also been in the area.
Police were called to Mercury Lane in central Auckland after reports of a disorder.
“We didn’t know what to think, cause there are incidents all the time including a bar fight on Saturday night,” she said.
“We were just wondering if it will get worse with the train station opening.”
She said security at her building had been increased.
On Saturday night, a fight at a Karangahape Rd bar sparked a large police response after officers were called to reports of fighting inside the venue before being called back when more fighting broke out.
Police on Karangahape Rd on Saturday night.
About 500 people were inside the bar at the time.
Seven people were arrested, although six were later released without charge.
One person was charged with assaulting police.