I go off to the side and call 911, that is how I help. I do not get directly involved because it can be dangerous. One my hubby and I were walking, a female was being forced by her bf to go with him. She asked for my phone and of course i let her use it. I tried to take her away and my bf dealt with the guy in a calm manner now the guy managed to pull her to the side and asked if she really wanted to get us involved, and I sensed he had gun on him. Luckily I had her number so I called her family after we got to a safe distance and flagged down two cops where made it clear they were on lunch >.>

Point is, try not to get involved, step to the side and call 911. Its safer. At the very least.