The Mexican government has sent federal police to take over security in a city in the southern state of Guerrero following the disappearance of 43 students and the discovery of a mass grave with dozens of burned bodies. The students, who are from a rural teacher’s college, have been missing for well more than a week after police and unknown gunmen ambushed their buses near the small city of Iguala, where they had gone to solicit donations for their school. Twenty-two police officers have been detained, and the city’s mayor and police chief appear to have fled rather than face questioning. The police have been accused of collaborating with a drug gang called Guerreros Unidos. Mexican President Enrique Peña Nieto vowed to bring the perpetrators to justice.

President Enrique Peña Nieto: “I particularly regret the violence that has occurred and, above all else, that they are mostly young students who have been affected and their rights violated in the municipality of Iguala. Mexican society, the families of the young people who unfortunately went missing are rightly demanding clarification on the incident and that justice be done, that those found be brought to justice and that there is no impunity in this case.”

Meanwhile, the families of the missing students have continued to protest the government, saying officials are not doing enough to find their loved ones. Macedonia Torres, the mother of a missing student, said authorities would do more if it was their child missing.

Macedonia Torres: “They will move heaven and Earth to find them. This is what we are going to do: We’re going to do whatever it takes to find them, and we will not rest until we do.”