Óscar Cervantes looked tired as he sought shelter from the harsh sun beating down on him and dozens of other men, women, and children manning a barricade that crosses the main highway linking Mexico City to the southern city of Oaxaca. He was defiant nonetheless.

"We're still afraid, of course," the 43-year-old teacher said, standing in the shadow of an overpass and sweating profusely. "What can you do against bullets? Just duck and get up again, I guess. But we must continue with our blockades and our marches."

Cervantes belongs to a radical teachers union named the National Coordinator of Education Workers, or CNTE, which built the barricade a week ago, with the support of locals from the town of Nochitxtlán, to protest against the federal government's sweeping education reforms. It came within a wider escalation of the protests across the entire state of Oaxaca that was triggered by the arrest of two local union leaders on money laundering charges.

Then, last Sunday, a massive police operation to clear the road sparked violent clashes and ended with at least eight people dead and dozens more injured.

The bloodbath suddenly turned the blockade at Noxchixtlán into a symbol of just how explosive politics can be in Oaxaca. It also brought criticism raining down on the government's use of live ammunition.

With the results of the autopsies not yet released, there is still confusion over the number of victims who died of gunshot wounds and who fired the guns that killed them. The authorities claimed an initial attempt to negotiate a peaceful retreat of the blockade failed and police only began shooting when they were attacked by thousands of radicals, some of whom were armed. The protesters claim the officers started firing without provocation.

Inhabitants milling about the town's main plaza on Monday evening were overcome with emotion as they struggled to understand what had happened the day before at the barricade.

"They killed members of our communities, of our families. Do you think we are just going to accept that?" one woman said, shaking with anger and asking for her name not to be published for security reasons. "We can't allow those people to come back."

After the clash, the government tried to calm the situation down by opening a dialogue with representatives of the striking teachers from the CNTE union for the first time in a year.

The talks began in Mexico City on Wednesday with both parties agreeing to continue the conversation on Monday. Nobody, however, is claiming that the conflict is anywhere close to a resolution.

A local holds bullet casings allegedly from the shootings on Sunday. (Photo by Jan-Albert Hootsen/VICE News)

The CNTE began life as a small dissident group within the much larger SNTE that has traditionally been allied with the government. Today it claims over 100,000 members nationwide, with the majority based in Oaxaca. It has been a thorn in the government's side ever since president Enrique Peña Nieto took office in 2012, because of its fervent opposition to his education reform.

Peña Nieto has insisted that the reform — which includes yearly evaluations of teachers and the threat of losing their jobs if they go on strike — will transform Mexico's dismal public education system. The CNTE claims the changes are a precursor to privatization and unfairly blame teachers for all the system's many failures.

At the same time the CNTE has sought to set itself up as a symbol of left-wing resistance to the political and economic elite, and nowhere more so than in Oaxaca where the teachers have a long history of channelling wider anger about poverty and inequality.

"The government tries to make the public believe it's all about the teachers, but it's more than just that," said David Estrada Baños, spokesman for the CNTE in Oaxaca. "There's much injustice in this country, and there are many people who join up with us because of it, people who don't agree with the government and join the struggle of the teachers."

With the talks still going on in the capital, Oaxaca's teachers are currently maintaining about 30 roadblocks around the state, some of them in strategic locations. The mood at the end of this week has been calm, but the tension remains palpable.

"I don't think, at this stage, anyone within the union is willing to give up the struggle, on the contrary," Baños added. "If anything, we'll march and block the highways with more resolve."

Cuauhtémoc Blas, the editor of the Oaxaca-based monthly En Marcha and a critic of both the federal government and the union, said he expects the CNTE will maintain its blockades across the state for the foreseeable future.

The analyst said that this could end up being "worse than in 2006," referring to a massive teachers' led movement a decade ago that paralyzed Oaxaca city for six months. That uprising was only controlled after the federal police occupied the city for weeks.

"Back then, the union and other allied social movements maintained a state of siege of sorts in the city of Oaxaca alone," Blas said. "Now they are doing it everywhere in the state."

The ramifications are already being felt.

Social media buzzes with complaints of sudden price hikes for basic food products in Oaxaca city. Some gas stations have run out of gas, reportedly thanks to the blockades.

Meanwhile, the tension remains high in Nochixtlán, where little has been done to clear up the mess left by protesters setting the municipal town hall ablaze on Sunday.

Just outside of town, broken computers and papers lie scattered across the parking lot of the abandoned offices of the federal police station. An antenna tower lies on its side crushing a lonely burned-out patrol car.

Back at the highway, the radicals in Nochixtlán have reinforced the blockade. They have placed the carcasses of cars, buses, and trailers in strategic locations, as well as heaps of dirt, logs, and stones.

"We're not going anywhere," said Luis Ángel, a 35-year old inhabitant of Nochixtlán who says he works in an administrative function for the union. "This is a city to which the teachers are very important. By attacking the teachers, they attacked the heart of the community. We're staying put, even if the police come back."