sympathies .... but you're ok to ride another day.
Have you reported it to the police? If not, then why not. It is common assault (or whatever the term is). More than likley they'll do F.A., but maybe they will, maybe the group hang round there and will get caught, espcially if you are able to describe the person.
Lots of maybe but don't sit there and do nothing. We pay for the police so get ya money's worth.