The Royal Canadian Mounted Police (RCMP) deployed Thursday to rescue about 500 pipeline construction workers who had been trapped since Sunday by native protest blockades against TC Energy Corp.’s Coastal GasLink (CGL) project in northern British Columbia (BC).

Reinforced RCMP squads established an access control point and stepped up patrols to clear protesters and barricades from the only route, the Morice Forest Service Road, into remote CGL work camps about 400 miles north of Vancouver. The pipeline would feed the liquefied natural gas (LNG) export terminal under construction on BC’s Pacific coast, LNG Canada.

The actions enforced a BC court injunction against interference with the project after truce overtures to the protesters failed, said RCMP Chief Supt. John...