Police in southern Mexico have found a mass grave in an area where more than 40 students are missing following a rash of violence last week.
Authorities say they have so far discovered the charred bodies of about 20 people on the edge of Iguala, in the restive state of Guerrero, 200 kilometers south of Mexico City.
Tomas Zeron, Mexican Federal Chief of Investigations, said, "A group of investigators and federal public prosecutor specialized agents are on their way to the site. The Mexican state cannot permit such an indignant incident to go unpunished. We want to emphasize that we will put all the forces of the state to shed light on this unfortunate event. Thank you."
Twenty-two police officers were arrested in Guerrero last week after a police confrontation in Iguala with student protesters.
Mexico is under fierce international scrutiny for years of alleged human rights violations by security forces.
Officials say the National Human Rights Commission has sent experts to the area to aid state authorities in identifying the remains.
Some information for this report was provided by AP and Reuters.