I suspect I know what really happened. All speculation.
They had all been drinking, and they went outside the bar to take a picture.
Obnoxious drunk intervenes: “Hey, man! Take my pi-chur too, wif’ my arms around these hot babes!” (Or much, much cruder words to that effect, and maybe some grabby.)
The three: “No! Go away! Get lost!”
Obnoxious drunk: (spews a lot of obscenities, cursing at them and calling the women offensive names).
The pushing begins. I suspect that it can be argued as to who started it. The tempers of the three flare.
Then obnoxious drunk threatens them all and stomps off, saying he intends to retrieve a weapon, or that is his claim.
Why they followed him is a good question, and generally dismisses any argument of self defense.
Most all of this is speculation of “the other side of the story.”
I know which scenario seems more plausible to me.