Lock-Down

Ali just texted me from her bus that Kat's school was under lock-down. I called and confirmed it with Kat's school. "The children are safe and they will be put on the buses when it is safe." Safe from what I wasn't told. So, I called Luke's school to see if his was locked-down as well.

"My daughter's middle school is locked-down and I am wondering if my son is also under lock-down."

"No ma'am, the doors are locked, the children are all safe, but we are not under lock-down."

"Oh, good, so you will be dismissing on time?"

"No, ma'am, the children are not allowed to leave the building."

Obviously, I have missed the overall meaning of lock-down.