critical condition. ken lee jones reports from florida. >> reporter: the train which derailed this time was a southbound freight of the atlanta and st. andrews bay railroad. a small line which operates between dothan, alabama, and panama city, florida. a tank car carrying poisonous chlorine gas was ruptured in the wreck. a deadly mist of gas spread from the tank car. motorists who were driving at night alongside the tracks were caught by surprise. most of the victim who is died were found in their cars along u.s. highway 231. >> people killed by poison gas, like they were on a battlefield in world war i or something instead of just driving their cars along a u.s. highway. amazing. after that, rail car accident in florida, and another one that same day in tennessee. and the other one that happened in waverly, tennessee, two days before that. federal investigators starting to look into whether this was maybe more than a coincidence. maybe there was some sort of systemic problem at...