MONTREAL – The calm of summer was shattered Monday with the return of school to Quebec universities, where some classes were disrupted as protesters disobeyed the back-to-school law.

Chaotic scenes, reminiscent of those seen across the province in the spring, suddenly flared up at two Montreal universities after a relatively quiet summer.

The province passed an emergency law, known as Bill 78, to set stiff fines for people who prevent students from attending class.

A tumultuous standoff erupted in the corridors of Universite de Montreal between security guards and masked protesters. The demonstrators were trying to spring seven of their comrades who had been detained by officials in a fourth-floor classroom.

Two protesters, their faces covered with clothing, warned a news photographer at the school that he had better not try taking pictures of them: “Be careful,” a woman told him. “They’re going to take care of you.”

Meanwhile, across town, masked demonstrators entered Universite du Quebec a Montreal and disrupted classes. Protesters also blocked cameras and one person taunted a journalist.

“It’s voyeurism,” the demonstrator muttered at the reporter.

The vast majority of Quebec’s students have voted to end their strikes, and the student unrest has hardly been an issue in the current provincial election campaign.

The return to junior college in recent weeks was peaceful, but Monday’s events, as universities reopened, were a flashback to events that captured international attention last spring.

During the showdown at Universite de Montreal, lines of guards stood shoulder to shoulder to block a hallway. They kept a couple of dozen protesters, most wearing masks, from getting close to the classroom where detained demonstrators were being held.

The guards faced a barrage of shouts and a couple of plastic garbage cans were tossed in their direction.

At one point, the protesters held a vote about whether to charge the line of guards. The group decided against rushing the line after not enough people in the huddle raised their hands in agreement.

Moments later, word spread that riot police had entered the building. The protesters scattered, knocking over garbage cans and chairs in their wake.

A fire alarm was also pulled, its sound wailing even into classrooms in departments not involved in the conflict.

One protester, who said he was caught between security staff and angry demonstrators, sported several red finger marks on his neck.

“A security guard grabbed me by the throat and pushed me,” Marc-Antoine Bergeon said outside the school after the confrontation.

“It’s really intense because there’s so much negative energy.”

At UQAM, small groups of masked protesters, armed with lists, were seeking out classrooms in faculties where students voted to remain on strike. They were interrupting the classes by shouting and shutting off the lights. Some of the classes were cancelled.

Several professors attested to being in a difficult position.

One professor, who teaches students from departments that are on strike and others that aren’t, summed up his dilemma.

“I was hoping that either everyone would show up, or no one would show up — so I wouldn’t have to make the decision whether to teach or not,” said the professor, who declined to provide his name.

“If three students showed up, should I still have the class?”

As it turned out, when masked students barged into his class shortly after 9 a.m., he was there by himself and the class had been cancelled.

In one psychology class at UQAM, a masked protester attempted to convince another student of the democratic legitimacy of the disruption. The actions, he explained, came after legitimate strike votes were held by student associations.

“We’re only disrupting classes in departments that voted to strike,” he said.

But the student simply turned her back on the protester.

The striking students continued to bang on desks and blew an air horn until the professor raised his hands in frustration and cancelled the class.

Several striking students carried a flyer that listed the departments that voted to continue their strike.

On the back of the flyer there are spots for taking down names, the programs and email addresses of students who defy picket lines.

A Montreal police spokesman said officers did not enter UQAM because school officials never made the request.

Management at Universite de Montreal, however, asked the department to intervene, said Cmdr. Ian Lafreniere.

He said officers were only called in to remove protesters who had blocked two emergency exits, not to enforce Bill 78.

“There are some people who want to attend their class, there are some people who want to protest — we’ve got no problem whatsoever about that,” said Lafreniere, whose department dispatched dozens of armoured officers to the school.

“We just want to make sure everyone is safe while doing that.”

— With a file from Nelson Wyatt