IGUALA, Mexico — The chief prosecutor of Mexico's Guerrero state says authorities have found 28 bodies in a clandestine grave discovered on the outskirts of a city where police engaged in a deadly clash with student protesters a week ago.

State Prosecutor Inaky Blanco also said two gang hitmen have admitted killing 17 of 43 students missing in southern Mexico since last week, but that it would take at least two weeks to determine the students are among the bodies found.

He said the remains are too damaged for immediate identification.

He also said authorities haven't confirmed the gang members' claims.

The Associated Press and AFP contributed to this report.