"I could see him standing then swinging it around and he put it on his shoulder."
The man noticed an undercover cop car at the end of the street.
"I saw more and more police officers turning up and it was all on.
"Eventually he put the gun down, they asked him to walk into the middle of the road and lie on his stomach, then they arrested him.
"He was probably high on drugs."
The witness is not sure which gang inhabits the pad as he said they seem to have changed recently.
At this point in time no one was believed to have been injured.
A large number of police remained at the scene and were working to clear the address.