Well in my case it was because they are trained to be extremely aggressive so they have been known to knock people to the ground and put a gun to the persons head just for running in their direction.
I'm a girl though, they just hit on me.
Edit: also if I recall correctly they are allowed to shoot you if they have reason to believe you are a threat. I don't remember the exact wording of that line in the warning they handed out to us all.
[2:08:58 am] Moongoddess256: being asian makes you naturally good at ddr
[2:09:22 am] gnizmo: its a weird genetic thing
[2:09:30 am] gnizmo: goes back to hunting giant crabs in feudal Japan