Using heavy machinery and armoured cars the National Guard ploughed through the barricades of old sofas and broken down refrigerators, bags of rubbish and barbed wire. After weeks of protest in the city of San Cristóbal – protests that were provoked by university students demanding better security after the alleged attempted rape of a classmate but which spread nationwide as an outcry against President Nicolás Maduro – Venezuela's security forces called time.

Before dawn of Monday, as they tried to clear the barricades from the streets, the security forces again engaged anti-government protesters in pitched battles involving tear gas and molotov cocktails.

A decommissioned tank that had been dragged on to Carabobo Avenue by protesting students, however, remained in place and demonstrators vowed to continue their struggle against Maduro's government.

"The more barricades they tear down, the more barricades we will put up," said José Vicente García, a student leader and city councillor who has been co-ordinating the protests. "We are going to continue to reinforce our trenches."

The protests began more than a month ago in this western city amid growing distrust of Maduro, the successor to Hugo Chávez who died a year ago this month after ruling for 14 years, setting Venezuela on a path to what he called "21st-century socialism". The protests spread to Caracas and other cities, prompting a violent response from the government. At least 21 people have died and hundreds have been injured in the nationwide clashes.

On Sunday, the Táchira state governor warned that he would try to regain control of San Cristóbal, where students and mostly middle-class residents have been protesting since early February.

García said at least two students were arrested overnight and dozens of city residents had been injured. The regional television station did not broadcast its regular morning news programme, he added.

Student leaders say they no longer consider themselves the opposition but rather the "resistance". Last week they issued a manifesto demanding respect for the individual liberties that they say have been trampled by the socialist government.

Melecio Medina, a carpenter in the Las Flores neighbourhood of San Cristóbal and a Chávista – a follower of Chávez's ideas – said he cared more about freedom from poverty than the "economic freedoms" the students and middle class demand. "They are misguided. They want to take away all the help the government has given to us poor people so they get richer," he said through a small window in the front door of his wooden home.

But in San Cristóbal, Chávistas are the minority and the protesters are settling into a routine of self-imposed siege. In the mornings, residents rush about town trying to stock up on the few supplies on supermarket shelves, with shoppers waiting hours in queues that snake around the protesters' barricades. Individual customers are limited to two litres of cooking oil, one kilo of cornflour to make traditional arepas (corn cakes) and a pack of four rolls of toilet paper – when there are supplies.

"When you see a long line at a market, it's because they've got a shipment of something," said Mireya Quintero, a seamstress who had been waiting four hours outside the La 14 supermarket. "I'll buy whatever I can because you never know when there will be supplies again."

The food shortages are a cause and consequence of the protests. The rationing of basic food and subsidised petrol has been in place for years in this city close to the Colombian border because so much was being bought to be sold at higher prices in the neighbouring country. The governor's office estimates that as much as 40% of all food shipped to the city is smuggled across the border. And since the protests, with so many city streets blocked, just getting to a market has been a challenge.

Government supporters here say the shortages and protests are part of a right-wing conspiracy to topple the president, elected last year by a slim margin. "It is an insurrectional plan that is expressed at the barricades," said regional lawmaker Jonathan García, of the United Socialist party.

There is no doubt that many protesters would like to see Maduro ousted by any means. Others say they should try to work through the constitution, which allows for a recall referendum for any elected official halfway through their term.

Whatever the mechanism, protesters don't seem ready to give up the fight. Though several of the students' makeshift camps which they call "points of resistance" were burned down overnight, they plan to rebuild.

Fashioning gas masks from old soda bottles, foam rubber and vinegar-soaked rags, students prepared for the night. A television satellite dish served as a makeshift shield.

"They will not pass," said Santiago Jaramillo, defiantly.