I have seen many times people be quickly "locked out" when being laid off. A term for this in the UK is "garden leave" because you're still paid but you're told not to work or come to the office anymore.
As the case may be this makes sense in order to avoid any issues (from bad blood in the office to actively malicious actions) and, realistically someone being laid off is not exactly going to do their best work, anyway...
Edit: Personally I think a quick cut is better as it avoids having to continue going to the office when you know it's pretty much pointless and it allows to focus on your next step. The thing is that it brings home the fact that this was all a business arrangement despite all the emotional attachment we may develop over time.