I don't always believe in reporting incidents because sometimes people have a bad day. But in this case I would report that employee first thing in the morning. I would ask to speak to human resources first and then management. I hope you got the name but if not a good description will suffice.
Hail Gunther 7-2-2013
If at first you don't succeed, destroy all evidence that you ever tried.
"Some people never end up going crazy...what a truly terrible life they must lead." - Unknown