I'm not sure what I would do as a parent, but I think my first reaction would be to grab my kid and run. They seem like sitting ducks locked in a classroom. But, I also see the danger there could be in that. I imagine most parents showed up with a weapon and would protect their children as much as possible. It must be complex for a teacher to deal with parents that are out of hand when you did your best to follow the protocol. Don't they understand it's not a "rule" you made but a school-wide policy to keep panic at bay? Once disorder and chaos happen, those kids are in danger of being trampled or worse.