Ignoring can't be an option since it's an act of misbehaving and there is no point at all. better handle it with reacting so that the other person learns a lesson.. Better Use words first, if that doesn't help and the person is ignorant then go for fight.
Better first reach in safe zone and post that, reveal whatever the situation is to your fellow travellers. That will make everyone aware of this situation and you and other girls will be safe that moment onwards and if it continues, you can take legal action