But that is the staff's task to organize evacuation.
There are trainings
- well, at least in my place of work, which is a school.
We have trainings every year with the whole school being evacuated within mere minutes.
Every teacher knows the route by heart from whatever classroom and whatever floor (3).
We train under the strict glare of Fire Department Officers.
No Mercy!
I was once reprimanded for a slight mistake.
Aaaaargh!!!!

I never made it again!
I can do it now with closed eyes and with kids in tow.
And the pupils know the routes too
JMO
Oh, to add...
During these vital minutes
we have to count our pupils and make sure nobody is missing (in bathroom or corridor).
Children go in pairs in orderly manner.
(Absolutely no running to avoid accidents, like broken legs, etc.)
But...
Practice makes Perfect!