"A number of people were sitting on the concrete in handcuffs.
"Others were standing against the fence with a long line of officers in front of them."
The witness said he saw a number of teenagers outside a nearby property who "seemed agitated."
It is not yet known whether anyone was arrested or charged in relation to the event.
Several gun-related incidents in days
The incident comes after a number of firearms incidents around the city in the last two weeks - the latest before this a gunshot heard on Christmas Rd, in Manurewa, on Sunday afternoon.
Armed police were seen on the street - in the area close to Mahia Rd - shortly after a "loud bang" was heard between 2pm and 2.30pm that day, according to neighbours.
Police searched the area, but did not find a firearm. There were no reports of anyone being injured either.
A police spokesman said yesterday that officers were following positive lines of inquiry and speaking to a number of people to figure out exactly what happened.
On Friday night, just before midnight, police got a report of a punter being spotted with a gun at a bar in downtown Auckland.
Authorities arrived at the premises on Sale St that night.
Staff at the bar had already taken the gun from the person involved. Police said the punter was arrested for unlawful possession.
In that incident, no shots were fired and again, no one was injured.
About a week earlier, police turned up to Dr Rudi's Rooftop Brewing Co, on the Viaduct, after multiple shots were fired into the foyer ceiling in the early hours of Sunday, December 6.
It was later revealed the shooting is said to have happened after a woman caught the father of her child out drinking with another woman.
Can you help? Anyone with information into any of the incidents is urged to contact Police immediately on 105 or CrimeStoppers anonymous on 0800 555 111
