Has anyone had to hide and tell the kids it's an active shooter drill, only for an actual shooter to show up?

I had to do this yesterday, and I can't stop thinking about it. I was telling the kids to be quiet in case a shooter came in, and they wanted to know why, so I said, "It's an active shooter drill." The kids on the front row were hiding behind their backpacks so as not to be seen from the door. I hoisted a kid up to the top shelf of one of our bookcases so he could avoid being seen. Then we heard the shooter walking around and getting closer. The kids didn't know whether it was real or a drill. <br><br>I am still having flashbacks.