The state public security agency deployed a helicopter to join the search in the tense town of Iguala and surrounding communities after students from a teacher college went missing on Saturday, the state government said in a statement.
At least six people, including two students, were killed as municipal police and unknown gunmen shot a protesters and a bus in Iguala on Friday.
Students from the rural teacher university of Ayotzinapa are participating in the search. The student union said some comrades may be in the custody of the military.
The Guerrero prosecutor's office is in contact with the parents of the missing students to find out if some of them have come home, the government said.
The rural university students protested against what they consider to be discriminatory hiring practices that favor urban students.
Iguala municipal police chased the students, some of whom had seized passenger buses, and shot at them.
State authorities initially detained 282 local officers but released most of them, keeping 22 under arrest under suspicion of firing at the students.
Guerrero is one of Mexico's poorest and most violent states, marked by drug gang turf wars and frequent protests by teachers resisting reforms.