I was sitting outside of an anime con rave with some friends when people started streaming out of the rave in a hurry. Someone had set off pepper spray in the middle of the crowd. Never fully found out why but the two stories I heard were either that a guy got way too handsy with a girl or someone just did it for the lulz. (Either way it was a bad time for a lot of people and the paramedics had to be called for a few folks.)