It wasn't a random crime as some of the victims knew the suspect by face. It wasn't senseless act of violence because words were exchanged by both parties (in other words, *something* happened to cause this). It wasn't robbery because none of the victims were asked to give up their valuables.
So what was it? An altercation took place before the shooting. What caused it? We don't know at this point. What do we know? That some of the people involved, suspect and victim, have gang affiliation but may not be gang members.
Gang related shooting. If that's not what it is, then what is it? Random? Senseless? Robbery? I already went through that in my first paragraph.
No one is saying that <insert name> is a gang member. All they are saying is that it's gang related. For example, let's say my cousin sells crack out of his home. I visit him one afternoon and as I enter his home, money and crack is being exchanged. The buyer freaks out, pulls out his gun, shoots me and runs off. I may be a law abiding citizen with no narcotics history but you can bet this will be a drug related shooting case. Obviously, it makes sense.