We lost two of the more well respected people in our group. One gave her two week notice on a Friday just before the end of January. She ended up getting a call at home on Sunday night informing her she wouldn't be allowed in the building come Monday. That decision came back at management as she had client tasks no one was familiar with. Last Monday another person gave her notice and after 17+ years she was given 20 minutes to gather her things and exit the building while security stood nearby, but the three managers nearby disappeared until after she left. If your going to give notice be prepared to be asked to leave.
Just wanted to reiterate what @T4JUMpC-1qvv said. I've seen this happen at least twice as well. For some reason, notice equals being escorted out immediately. Paranoia or something else, I don't know.