Teachers, others block main Mexico City roads

Teachers, others block main Mexico City roads

A police officer is engulfed in flames after being hit by a Molotov cocktail thrown by protesters marking the anniversary of the Tlatelolco massacre in Mexico City, Wednesday Oct. 2, 2013. Mexico commemorated the 45th anniversary of the massacre of students holding an anti-government protest, killed by men with guns and soldiers ten days before the 1968 Summer Olympics celebrations in Mexico City. (AP Photo/Eduardo Verdugo)

MEXICO CITY (AP) -- Thousands of teachers and students blocked Mexico City's main thoroughfares during rush hour to honor victims of a 1968 massacre while pledging to fight to undo an overhaul of the education system.

A small group of self-described anarchists clashed with riot police, who used tear gas after the activists threw firebombs, bottles and rocks. Twenty officers were injured, and 20 people were detained.

Wednesday's protests and road closures are just the latest acts in what has become near daily disruption by demonstrations of the capital's life in recent weeks.

The education reform aims to break union control of the school system by requiring teacher evaluations.

The anniversary of the 1968 massacre of students by soldiers is often marked by protests and clashes.