[lizma]

"Because a lock-down means the kids can't leave, even if parents come to get them."

This is not true.
Code Blue means doors are locked, blinds pulled and the kids are not allowed outside. Parents CAN pick up their children whenever they want to.

[Bigg Red]

You describe a Code Blue correctly. I was referring to a lock down, a situation in which no one - parents or students included is permitted to leave or enter the school.