Bullies come in all ages, socio-economic groups, races, religious affiliations and both sexes. In order for bullying to stop the bully needs to be informed that this behavior is unacceptable and face real consequences. If you ignore this behavior it will continue. I would advise using any means you can to address this problem because if you ignore it it will continue. I think talking to HR is an excellent start but hopefully your meeting emphasized that you will not accept this kind of behavior and direct action needs to be taken and immediately!!! Problems like this at work are especially challenging because you have to see these idiots on a daily basis. Let us know how this turns out, my friend. Hang in there!