Teachers from the radical National Coordinator of Education Workers, or CNTE, are protesting education reforms introduced by Mexican President Enrique Peña Nieto that introduce teacher evaluations.

Union members have set up blockades on some major highways across Mexico. In June, a clash between police and teachers at one of the blockades in Oaxaca left eight protesters dead and dozens wounded.

Tensions are particularly high on the road that connects Oaxaca to Mexico City. Authorities say those impacted by the blockades have run out of patience, and the government is threatening to use force again to clear the roads.