CNN  — 

When Farid’s friend called crying for help on Sunday, he jumped on his bike and quickly rode to Tehran’s Sharif University.

“Please come save us. We are stuck here. They are shooting at us,” his friend said.

Scenes of violence and “savagery” met him when he arrived at the campus of the elite university, he said, where hundreds of students had been trapped in the parking lot by Iran’s Revolutionary Guard Corps, according to videos CNN verified from social media.

“They had guns, they had paintball guns, they had batons,” said Farid, whose name has been changed for his safety.

“They were using gases… [that are] banned internationally… it was a war zone… there was blood everywhere.”

In one video posted to social media from the scene, police can be seen detaining people and carrying them on motorbikes. In another, loud bangs are heard.

It was the first day of school, but many students had refused to join class. Instead, they were protesting against the regime, in a nationwide movement triggered by the death of Mahsa Amini, a 22-year-old who passed away last month in a hospital after being apprehended by Iran’s morality police and sent to a “re-education center” for not abiding by the state’s hijab laws.

For more than two weeks, protests have taken place in more than 45 cities across Iran, including the capital, with dozens of people reportedly killed in clashes with security forces.

CNN cannot independently verify claims of arrests or detentions as a precise number of protesters arrested or detained is impossible for those outside Iran’s government to confirm. Numbers vary depending on whether they come from opposition groups, international rights organizations, or local journalists. State media outlet the Islamic Republic of Iran Broadcasting (IRIB) reported that at least 41 people have died in Iran in recent protests. According to Amnesty International, the crackdown has killed at least 52 people and injured hundreds more.

While the rallies started with calls for justice for Amini’s death, they have since morphed into a larger movement, uniting an array of social factions and classes.

Farid said that Sunday’s incident began after a group of students were reprimanded by campus security – who called in reinforcements – for staging a walkout and engaging in anti-regime chants.

“It started with the students refusing to go to class. And then the (professor) of science came to talk to them because they were chanting stuff… the students were led out by the security forces of the university, and they were then stopped by Sepahs (IRGC forces), wearing normal people’s clothing,” Farid told CNN.

“They told them that ‘if you go near the subway station, we will start shooting, go back to the university.’ And then after half of the students got back into the university, they let the others into the parking lot. And after that, they started shooting them with paint balls and taking them into custody in a very, very savage way,” he added.

The university’s official newspaper, the Sharif Daily, also reported that security forces fired less-lethal rounds at large groups of students in the campus parking lot while they attempted to flee from security forces on Sunday. Social media videos reviewed by CNN captured the incident.

The “three main dormitories” of the Sharif University were also “shot at” by security forces, according to Farid, who claimed that there are still students hiding out at the university following Sunday night’s events.

“As we speak, there are still students hidden in the university in the parking lots or in professors’ rooms,” he told CNN.

“We don’t have a tally [of detainees] yet. The Student Council was trying to make a tally, but we won’t know for sure for another five, six hours.”

Citing a source at the university, Iranian state news agency IRNA said Monday that 30 of the 37 students arrested during the protests had been released.

CNN cannot independently verify what happened during the confrontations at Sharif University or the number of students detained in the aftermath. Representatives from Sharif University could not immediately be reached for comment.

In a statement Monday, the Sharif University Students Islamic Association urged all “professors and students at Sharif University not to attend classes until all arrested students are released” while calling on students and professors across Iran to pause classes in solidarity.

Snippets of that ongoing solidarity have already been seen in the Iranian capital, where video posted to social media shows a line of cars blocking the streets near Sharif University on Sunday night in support of the students.

The nationwide protests – which bring together a combination of grievances over a floundering economy, limited civil rights and the marginalization of ethnic minorities – are the most significant domestic threat the Iranian regime has faced in years.

Today’s protests are also bringing together younger Iranians with internet access who haven’t known Iran before the Islamic Republic.

It’s unlikely that the government – which has blamed Western media for instigating the protests – will make concessions, analysts say, with an end of the demonstrations more likely to come through the use of brute force.

But Farid insists he and his contemporaries are not scared, saying they have nothing to lose.

“This is far from over. We are not scared. We are outraged. We are furious. You know, these people think that we are the previous generation – that if they do this, we’re gonna just stop. We are not going to stop,” he said.

“These kids are our future,” Farid added. “We’re not going to stand for this.”

CNN’s Adam Pourahmadi and Ramin Mostaghim contributed reporting.