Jump down into tracks, and head left. Kill gunman in the fog, after you run into scared innocent. Train will pass by. The second cubbyhole has a homeless innocent in it. Be careful of fire.
Third cubbyhole has a gangster in it.
Clear four bad guys and continue. Sabre will run like a coward as you catch up with him. When you meet up with Hawk, Sabre is ditching the scene on the top of a train. Jump down on top of train to the left of Hawk. If you miss, don't worry, you can chase Sabre on foot down the tracks.