Police have stormed schools in the Chilean capital Santiago to evict students who have been staging a week-long occupation.
It is the latest in a series of protests by students demanding reforms to the educational system in the South American country.
Police arrested 139 people, mostly teenagers, when they entered three high schools in the downtown area that had been taken over by students.
Students from around the country study at the three prestigious public schools - Dario Salas, Miguel de Cervantes and Confederacion Suiza - often with government scholarships or at a low cost to the parents.
"The use of force was necessary for the rule of law," said police chief Victor Tapia amid allegations of excessive use of force.
The student movement erupted last year as calls for sweeping education reform, free college education and central government control over public schools mounted.
High school students say right-wing President Sebastian Pinera has failed to hear their demands.
Public education in Chile suffered from sharp cuts in funding during the 1973-1990 dictatorship of Augusto Pinochet, leaving a system that favours expensive private schools that are out of the reach of the poor.
Santiago mayor Pablo Zalaquett ordered the evictions after meetings with student representatives failed to result in an agreement that would allow classes to resume.
"I would have liked for there to have been no arrests," Mr Zalaquett told Radio Cooperativa.
The people who were arrested "were given every opportunity to leave peacefully but unfortunately they did not", he said.
Protesters left the Miguel de Cervantes school peacefully, but they resisted at the other two schools.
Student protest organisers have called for more demonstrations demanding reform on August 23 and 28.