Muscatine

Here's another version of how this might play out.

I'm sitting there enjoying the game with my same sex partner.   You're sitting 8 rows behind me.   A guy a couple of rows ahead of me pulls out his gun.   You've been sort of paying attention to the game but luckily do see him before he fires so you remove your weapon from where you were hugging it to your breast and you put a bullet through the guy.   Unfortunately it continues on through two other students, killing both.

Then, dang, you find out he pulled out his gun because he thought someone else was threatening people with a gun.   So you shot three people by mistake.   For nothing.

There's another gun lover sitting 8 seats to your left who sees you start shooting and killing three people.  He assumes the worst, (correctly) that you're a crazy gun nut, and stands up aims down the row of seats.   First shot hits a lady who was scared of all the shooting and jumped up between he and you just as he shot.

The next shot misses and kills a guy to your right.   Third shot nails you.   You return fire before dying.  Others of your ilk notice all the shooting and start to also shoot the shooters.   Of the 50,000 in the stands, maybe only 10 or 20 are fatally shot before it stops.   Of course, what would stop it?   How would all the shooters know which were good and which were bad shooters?   Do you boys have a secret sign to let others know you're a nice guy and shouldn't be shot?