My worst fear?

Ever since I became a teacher, my worst fear has always been that some nutter might burst into the classroom one day weilding a knife or gun and do serious damage (I know that sounds weird, but whenever I've heard about it happening elsewhere I've always wondered how I would cope with it. Well today it has happened about 500 metres from my classroom. The police are (as I speak) in a seige with some guy with two samorai (spelling?) swords who's in one of the houses nearby. My classroom is at the front of the school, so you can see it all from our window. To be honest it'd had been going on for a few hours before we even realised(!), and they obviously didn't think it was enough of a problem to evacuate, but it is still scary seeing all the police vans, dogs and riot gear. Home time was fun as no one could get down the road to pick up their kids, they had to go the long way. It's all quite scary!