Authorities have accused local police of involvement in shootouts the night of September 26 , when gunmen opened fire on buses carrying dozens of students and soccer players . Mexican federal forces are taking over security in the town of Iguala . Many students went missing there more than a year ago , and mass graves were found . ` ` I am outraged and troubled by this tragedy , '' Mexico 's president says .
Mexican federal forces are taking over security in the town of Iguala . Many students went missing there more than a year ago , and mass graves were found . ` ` I am outraged and troubled by this tragedy , '' Mexico 's president says .