IGUALA, Mexico (AP) — State officials worked Monday to determine whether 28 bodies found in a clandestine grave are students who were attacked by police suspected of drug gang links. President Enrique Pena Nieto called the deaths “outrageous, painful and unacceptable.”

Guerrero State Prosecutor Inaky Blanco said the bodies are badly damaged and that genetic testing could take two weeks to two months to determine if they are some of the 43 college students reported missing after the violent confrontation in Iguala, located about 120 miles (200 kilometers) south of Mexico City.