Indigenous leaders, lawmakers, students, and environmentalists took part in a massive day of action that stretched across Canada on Friday to protest the expansion of Kinder Morgan’s Trans Mountain tar sands pipeline, a project Canadian Prime Minister Justin Trudeau has said he will “ensure” is completed.

Calling out the prime minister by name, demonstrators hoisted signs and banners proclaiming, “Climate leaders don’t build pipelines.”

In what was called a first in Canadian history, two sitting members of parliament—Green Party leader Elizabeth May and New Democrat Kennedy Stewart—were arrested for demonstrating against the Trans Mountain pipeline outside of the gate of a Kinder Morgan construction site on Burnaby Mountain, where indigenous leaders staged a sit-in last weekend.

“This is because of Justin Trudeau’s betrayal of British Columbia,” Stewart said as he was led away by law enforcement. According to Vice, more than 100 pipeline protesters have been arrested this week alone as opposition to Kinder Morgan’s project mounts.

While crowds of demonstrators marched in Canada’s capital or took part in one of the 50 actions that took place across the country, others occupied Kinder Morgan offices to voice their opposition to the company’s project, which Indigenous tribes and green groups say would severely endanger the water supply and the climate.

“Kinder Morgan does not have consent for this project,” said Anna Gerrard, an activist with Climate Justice Edmonton who participated in a sit-in at Kinder Morgan Canada’s downtown Calgary office on Friday. “Second to this, our ability to proceed with a national climate strategy should not be negotiated around the construction of a massive fossil fuel project.”