Mexican officials say they have found a clandestine grave holding an undetermined number of bodies outside a town where violence last weekend resulted in six deaths and the disappearance of 43 students.

Guerrero State Prosecutor Inaky Blanco says the grave is on the outskirts of Iguala, which is 120 miles (200 kilometers) south of Mexico City. He isn't saying how many bodies might be there or whether any could be some of the missing students.

State officials have said that last weekend's bloodshed in Iguala started when city police shot at buses hijacked by protesting students, killing three students and wounding 25. Masked men later fired at vehicles on the highway, killing two people on a bus and one in a taxi.

Homicide charges have been filed against 22 policemen.