Inject a bit of slow poison into the water bottles they hand out for free or give for free water bottles with the pride flag colors(nobody will suspect it's to hide the poison if it has color) and from the top so nobody will notice.
After a few hours a few people will collapse.
When it'll be evening people will start noticing critical damage but idk what will be good for it.
Or just make drones with explosives on them and a bit of
Dimethylmercury in a container, hopefully they'll think it wasn't more than a bit of explosive threats
