"What I can confirm is that two individuals received injuries consistent with gunshot wounds, one of which is critical and fighting for his life as I speak.
"The other male also received critical injuries, however, they are not thought to be life threatening at this time.
"Other males that were also involved in the disturbance have received an array of injuries all believed to be serious."
Since the six men were admitted to hospital in the city, four have been discharged.
Supt John McBride said officers would be patrolling the area to reassure the local community.
He said: "It happened in a sunny Saturday evening when children were undoubtedly out playing in the area and if you're a parent there and you've got a young kid, you probably want that feeling of safety."
He added: "It is important for people to know that this was not a random attack, it was a targeted attack involving two separate factions."
"It was such a large inciden