My school was threatened with a shooting just after I left by 2 morons, the idea never went further than what I imagine was a crude drawing pinned to a fridge door. They basically said they wanted to fill a van full of explosives, drive and detonate the van in the shopping center 5 minutes away from the school, and then raid the school with guns. They were find out before anything even happened, the news showed footage of them with homemade explosives in their garden, but they were fucking fireworks. It was pathetic, they probably don't even know where to buy a van, let alone bombs and guns.
Apart from that, nothing really happened. A few people in my year were kicked out for selling cocaine, I find that quite funny though.