article_snippet.sent: At the time, A freight train carrying a dangerous form of ammonia was carrying anhydrous ammonia - a highly toxic, nitrogen-based chemical that can form explosive mixtures with air.
article_snippet.sent: A freight train carrying a dangerous form of ammonia was also transporting non-hazardous ammonia nitrate .
article_snippet.sent: : At the time, the vehicle was carrying anhydrous ammonia - a highly toxic, nitrogen-based chemical that can form explosive mixtures with air.
article_snippet.sent: the vehicle was also transporting non-hazardous ammonia nitrate .
highlights_snippet.sent: Norfolk Southern train was transporting anhydrous ammonia - highly toxic, dangerous chemical .
  