(CNN) -- Tens of thousands of protesters unhappy with planned tuition hikes in Quebec took to the streets Tuesday afternoon in Montreal to mark 100 days of demonstrations.
After a weekend of clashes, tension at first subsided because organizers of the downtown rally provided an itinerary in advance, as required by an emergency law passed late last week, police said.
Still, the protesters, many wearing red, split into three groups, with only one column following the prescribed route.
Montreal Police Cmdr. Ian Lafreniere said there had been no arrests in the afternoon protest. Police were unable to detain suspected anarchists who threw rocks and broke bank windows because they ran toward another group of protesters, he said.
"Luckily it's been raining," he told CNN.
But some protesters wearing masks threw objects at police officers in another march Tuesday night, said police spokesman Daniel Fortier. Six people were arrested. Police had warned demonstrators three times that their protest was illegal, Fortier said.
Police would not provide crowd estimates.
Tuesday's protest was intended to denounce tuition increases and Bill 78, which requires organizers of a demonstration with more than 50 participants to provide written details and the route of the event eight hours in advance.
"The exercise of democracy has to be done without disruption to ensure that no unfortunate event take place," police said.
CLASSE, considered the most militant of the province's three main student associations, has said it will continue to protest without giving police an approved itinerary, according to CNN Canada affiliate CTV.
"We are witnessing the biggest act of civil disobedience in Canadian history," read one post on a CLASSE Twitter page. "We have a rendezvous with history, and we won't miss it," read another.
Tuesday's march was planned by a coalition of 140 community groups and unions, some of which said they're heeding the new legislation.
At least 300 people were arrested and 20 were injured in Montreal during weekend clashes between police and protesters, according to CTV.
The movement began after a proposed tuition hike of $1,625, which would be implemented over several years.
Lafreniere said police have made about 1,000 arrests since the protests began.
"It's day by day. It's a peaceful city, normally," he said.