Thousands of protesters marched along the famed coastal boulevard at the Mexican resort of Acapulco to demand the safe return of 43 missing students from a rural teachers' college .

The government is combing the hills of southern Guerrero state with horseback patrols and is sending divers to look in lakes and dams, but has not found the youths missing since Sept. 26.

Protests hold out hopes they are alive, and have pledged to blockade city halls throughout the state until they are found.

A caravan of more than 20 buses from the college joined other protesters from the state's teachers' union in downtown Acapulco Friday for an emotional but peaceful demonstration three weeks after the students were reportedly taken away by local police and members of a drug gang.