(AP) - With the thunderous crack of a freight train slamming into a parade float, instinct kicked in for Sudip Bose. A front-line physician in Iraq, Bose and other veterans instantly tended to the injured after the train traveling more than 60 miles per hour in West Texas crashed into the float. It was carrying wounded war veterans and their spouses. Four veterans of Iraq and Afghanistan were killed, including an Army sergeant who'd pushed his wife off the float to save her. Sixteen people were injured. Bose said Friday that the aftermath reminded him of a combat triage situation. Investigators are still trying to determine whether the small parade had been given enough warning to clear the tracks. They hope that cameras on the train and a sheriff's vehicle provide some answers.