An estimated 10,000 Mexican teachers, many of whom have been targeted in extortion rackets run by criminal organizations, took to the streets of the Pacific resort city of Acapulco on Wednesday to demand greater security.

The demonstrators, who say criminals have barged into schools in recent weeks to demand protection money from teachers, called on Guerrero state authorities to step up vigilance at those establishments.

"They're constantly sending us text messages (by cellphone) demanding half our salaries as protection money," a teacher who has been working in that profession for 30 years said.

The educators, members of the SNTE and CETEG unions, walked roughly three kilometers (1.8 kilometers) along Acapulco's emblematic Miguel Aleman Ave. to press their demands.

"They've kidnapped three teachers in the past few days and they're demanding money for their release. We're afraid to return to our schools," said a young educator from an indigenous town in Guerrero's highlands who teaches in Acapulco.

A total of 315 schools have been shuttered for a month due to teachers' fears of extortion rackets.

On Wednesday, the teachers set up a roadblock on Miguel Aleman, a wide tourist boulevard, and say they will not move from the spot until Guerrero Gov. Angel Aguirre Rivero meets their demands.

The state government pledged two weeks ago to beef up security at schools and their surrounding areas and install panic buttons that can be used to call police.

The teachers say they also fear the municipal police because some officers are protecting the interests of organized-crime gangs.

Guerrero state, whose mountains are a prime growing area for illegal crops, has been the scene in recent years of a war between rival drug cartels that left 370 people dead last year in Acapulco alone.

The state, which suffers from a high level of poverty, has also been affected by other types of conflicts, and guerrilla groups have sprouted up there.