MONTREAL - It was another chaotic night in downtown Montreal.

For the second night in a row, police clashed with protesters repeatedly into the late hours Sunday in a chaotic scene that left at least 300 arrested and 20 injured, including 11 police officers. At least one person was taken to hospital with what emergency services called "non-life threatening injuries."

Windows were smashed, construction cones and signs tossed into the streets, and there were reports a fire hydrant was burst open at the same spot where a bonfire was lit a night earlier.

Riot police used tear gas and sound grenades to try to break up the protest, which was deemed illegal moments after it began for not complying with the new law. The result was a series of violent exchanges between small groups of protesters and police in pockets throughout the downtown core.

One video circulated online (see below) captured what appeared to be a police cruiser moving forward briefly with a protester on the hood, before the protester jumped off to the side and the cruiser sped away. Police later denied a rumour that a person had been run over.

"This is not a good thing to do," said Lafreniere. "You don't stop a vehicle with your hands, but again this is part of common sense. For the officer, imagine for instance, this officer was getting rocks at his vehicle. Imagine he stopped his vehicle, getting out of the vehicle to stop this pedestrian. It could have been a riot and yes he could have been using his firearm."

Another video featuring a police officer pepper spraying people after a short verbal confrontation was also posted to YouTube (see second video below).

Montreal police called in the Surete du Quebec for backup this weekend, while dealing with a near-record number of arrests.

The SQ was brought in to give exhausted local police officers a break, said Montreal police spokesperson Ian Lafreniere.

"A lot of officers are doing 12, 16, 18 hours a day, confrontations with people throwing rocks at them, and we saw a Molotov cocktail last Friday, so yes, it's getting crazy," he said.

Protesters accuse police officers of being too forceful.

"Have you seen the police in action? I was arrested for walking on the sidewalk the other day," said on person who spoke with CTV Montreal.

Lafreniere said the stress is affecting some officers.

"We're not perfect... and officers getting threats also, on them and their families," said Lafreniere.

Two journalists from local newspapers also reported being arrested and later released.

The legislation passed Friday was intended to put an end to three months of student protests, but it appears only to have given the movement momentum.

"I think the government put the police in a difficult situation," said protester Nino Gabrielli, who got his Master's last fall at a Montreal university. "I think the population is mobilizing around this thing."

Police were newly armed on the weekend with Bill 78, which lays out regulations governing demonstrations of over 50 people. It includes requiring organizers to give eight hours' notice for details such as the protest route, the duration and the time at which they're being held.

The City of Montreal also adopted a new bylaw that threatens protesters who wear masks with heavy fines. But it failed to deter dozens of protesters from wearing masks Saturday or Sunday night, and police said they would use the new law with discretion.

Montreal police took a tougher stance on the weekend than previously seen during the nightly marches. The march was almost immediately declared illegal on both Saturday and Sunday because, police said, they weren't provided with a protest route and bottles and rocks were thrown at police.

Meanwhile, the international hacker group Anonymous hacked into the Quebec government public security's website, the latest in a series of apparent cyber attacks against the province.

A post on the hacked web page warns the government to be fearful of the group.

With a report from CTV Montreal