Good thought Patrick, but would you really jump in with a 340 pound ex-con? Perhaps those people in the place know something you don't know. Have you ever had a gun pointed at you? Have you ever been in a situation like this?
Please understand, I think the public should be more involved in crime, but at the same time, you must put yourseld in their situation. I remember when I was living in New York I saw a lady get her purse snatched. I chased the guy into a building. He stood there with about five other guys and told me to come on and get her purse. I just waved and said good luck...