Two lockdowns ever for me (real)
4th Grade - Found note in the bafroom said there was a bomb
6th Grade - This kid who is now Burnt Steven put a switch-blade up to my Math Teacher (Mrs. Mock)'s neck.
Burnt Steven was having an oil fight and there was oil on him then he put oil on the end of a stick and lit it with a lighter setting him on fire and burning the stuff out of him (And he smells like burnt loving chicken)
EDIT: 3 times :P
2nd Grade - Some weird hobo sick dude walked in our school and we had to hide :D
And for the leaving school thing, in 1st grade there was supposedly a tornado coming to me (I lived in Baltimore City)