It's now clear that this was a planned action and there was no danger.
But when it happened, this wasn't obvious in any way. I assume the
other staff members knew about it, was it discussed at the last meeting?

I really like April Fools, but this was no April Fool. Faking a crime,
in this case claiming to have been hacked, is no prank or joke. It
doesn't matter that it was April 1. either. This was absolutely
unacceptable, never do this again!

Regards,
Daniel Abrecht