The second victim died early Tuesday morning from wounds sustained in the shooting.
The identities of the victims have not been released.
Police say the shooting stemmed from an argument between two groups having barbecues on Belmont Plateau around 8:00 p.m. Sunday.
According to investigators, a man from one group shot two men in the other group.
One of the victims was pronounced dead a short time after the gunfire.
Police said shortly after the shooting that someone had been arrested, but clarified on Tuesday that someone was apprehended, but later released without being charged.