article_snippet: Scroll down for video .
article_snippet: The man, who used to be in the military, ran afterMark Katchem of Chicago and tackled A man whose name has not been released to the ground.
article_snippet: A man whose name has not been released ordered Mark Katchem of Chicago to stay on the pavement and held A man whose name has not been released at gunpoint until police could arrive on the scene.
article_snippet: A man said: 'I immediately knew by the way A man was standing,
article_snippet: A man stance, A man was in control of the situation. '
highlights_snippet: Grabbed gun from Man car and kept suspect on the ground until police came .
  