Victoria police say its officers took 13 people into custody following an occupation protesting the Coastal GasLink pipeline project.

The group had started a sit-in in the lobby at 11 a.m. PT at the provincial government building in the 1800-block of Blanshard Avenue on Tuesday.

The youth are supporting Wet'suwet'en hereditary chiefs who oppose the 670-kilometre LNG pipeline project from B.C.'s northeast to Kitimat on the coast.

Coastal GasLink has signed benefit agreements with all 20 elected band councils along the route. But the hereditary chiefs argue band councils only have jurisdiction over reserve lands, not unceded territories.

The B.C. Supreme Court has granted an injunction against the pipeline's opponents who have set up camps close to a work site near Smithers. It authorizes RCMP to arrest and remove anyone contravening the order.

Supporters attend a protest in downtown Victoria against the Coastal GasLink pipeline. (Madeline Green/CBC)

Nigel Henri Robinson, who was at the occupation, says police showed up overnight.

"At one or two in the morning all the media was gone and that's when all the police started to come in," Robinson said.

Victoria police say officers worked with representatives from the protest group and the province to find a peaceful solution in the early hours of the occupation, as plainclothes community liaison officers attended and remained on scene.

When negotiations failed around 2 a.m., It says officers were requested to remove the protesters by the building owner.

The arrests took place over a four-hour period, police say, and "the minimum amount of force was utilized to effect the arrests."

In all, 13 people were taken into custody. No charges have been laid.

Sii-am Hamilton of the Nuu Chal Nulth Nation says more than half of the people participating were arrested, including the mother of one of the young protesters.

"She was only there to hold space and share medicine and songs and keep the youth that were locked down safe. She was screaming and afraid," Hamilton said.

A group of youth and their supporters — around 50 people in total later rallied in downtown Victoria. The protest ended just after 9 a.m. Wednesday.

Premier John Horgan has sent a letter to Chief Na'moks, a spokesperson for the hereditary clan chiefs who also goes by John Ridsdale, suggesting a meeting with a representative of the B.C. government.