MONTREAL -- Police have served protesters blocking rail tracks south of Montreal, in St-Lambert, with an injunction demanding they dismantle their barricades.

CN police just before 7 p.m. on Thursday approached the barricades with a box full of paper, delivering copies of the injunction to the protesters. Officers said they would give the protesters time to read it. It was unclear as of Thursday evening if police would move in against them.

Longueuil Police had tweeted just before 7 p.m., warning motorists to stay away from the area to allow the demonstrators to leave. 

The protesters, however, showed no signs of leaving.

Canadian National earlier had obtained the injunction to end the blockade of its railway line in Saint-Lambert that had snarled commuter rail traffic to Mont-St-Hilaire and Via Rail service to Quebec City.

Quebec Premier François Legault had said that the barricade would be dismantled by municipal police on the South Shore when the injunction was issued. Longueuil police had asked for the Surete du Quebec's assistance to remove the barricades, should officers attempt to intervene.

Early Thursday afternoon the protesters were reluctant to speak to the media, though some locals had engaged with them. "I support you, but it's enough," St-Lambert resident David Skitt told the protesters, urging them to get off the tracks. After his conversation, where he expressed his frustration with their methods, he shook hands with one of the demonstrators and left.

Temperatures overnight Thursday were predicted to dip as low as -16 C with a windchill of -22 C, according to Environment Canada. The demonstrators had lit a fire inside of a tent and asked their supporters for wood, supplies and blankets.

The blockade of the railway line by supporters of Wet'suwet'en hereditary chiefs has delayed the planned resumption of Via Rail service between Montreal and Quebec City. Service on the busy corridor was set to resume Thursday, but Via Rail announced that the resumption has been postponed until at least the end of the day Friday. The new blockade gave Via Rail "no other option" to push back the resumption of service, the company said in a statement.

Service between Montreal and Ottawa is scheduled to resume Saturday. Service on the complete Windsor-Quebec City corridor is currently expected to resume Sunday.

On Wednesday, Via Rail announced that it was temporarily laying off some 1,000 employees due to the impact of blockades across the country.

Blockades of railway lines across the country have caused widespread passenger and cargo train delays and cancellations.

The blockades are being set up in solidarity with the hereditary chiefs of Wet’suwet’en First Nation of northern British Columbia, who are opposing the construction of a new pipeline through their territory.

- With reporting by The Canadian Press.

This is a developing story that will be updated.