A powerful Mexican cartel has allegedly taken responsibility for the kidnapping of four U.S. citizens, and killing of two of them, in Matamoros. WATCH FULL EPISODES OF WORLD NEWS TONIGHT: https://abc.com/shows/world-news-tonight WATCH WORLD NEWS TONIGHT ON HULU: https://bit.ly/3iQLwPp #worldnewstonight #abcnews #mexico #cartel #border