British Columbia (BC) natural gas consumers were warned Wednesday to expect service disruptions after a pipeline exploded and caught fire late Tuesday, shutting down the province’s main supply from northern production fields.

Distributor FortisBC estimated that 70% of its one million customers were vulnerable to supply losses as a result of the mishap on a remote leg of Enbridge Inc.’s Westcoast Transmission, near the northern industrial city of Prince George.

Consumers have been asked to restrict gas use until more is known about the damage and a schedule for repairs, the utility said. Westcoast likewise posted warnings to shippers that traffic on the line has been stopped until further notice.

Spot gas markets continued to rally on Wednesday, with markets across the western United States posting substantial day/day gains after Canadian imports became restricted following the explosion.

Northern shale drilling has prompted capacity expansions that have increased traffic on the 61 year-old BC pipeline to a range of 1.7-2.0 Bcf/d. In addition to supplying gas markets across the Canadian province, Westcoast delivers exports into the northwestern United States supply grid.

Importer Northwest Pipeline LLC posted a notice to shippers today that echoed FortisBC’s warning: “To the extent Westcoast cuts the gas at Sumas [Washington, the system’s border crossing], Northwest will pass corresponding cuts to the delivery points. Northwest requests all customers to take immediate action to reduce loads on the system.”

Westcoast crews were examining the pipeline and developing repair plans. The National Energy Board and Canadian Transportation Safety Board have dispatched inspectors and accident investigators to the spot where the pipeline broke. Police temporarily evacuated a nearby native settlement but most residents returned home. No injuries or environmental damage were reported.