This is unfortunately a common result.  Bees do not normally gather honey.
They go after nectar, which is not nearly as dense.
 
Honey is so thick and sticky the bees who fall into or on it in all the
melee usually get stuck.  The more they move to try to get out, the more
they get bogged down.  A number often will fall in and evidently suffocate
as the honey coats their abdomens.
 
Honey also has a concentrated aroma which can make the bees really excited.
I have seen some fighting and overall commotion in such a situation, with
the bees all confused and many falling into honey, getting stuck.
 
Once there are several bees floating in/on the honey, the others can land
on them and feed without getting caught!
 
When I am done using my small extractor I usually tip it sideways, downward
at an angle and put a sheet of plastic or boards down, so the honey will
have someplace to run and collect, spreading out the surface area to allow
the bees access without so many falling in.