FortisBC is warning that the majority of its approximately one million gas customers could lose service as a result of Tuesday's pipeline explosion north of Prince George.

While no FortisBC infrastructure was damaged when the Enbridge pipeline ruptured and ignited, the utility relies on the pipeline to supply natural gas to its customers across the province, including in Metro Vancouver and the Fraser Valley.

Two pipelines have been shut off while crews respond, and FortisBC estimates about 70 per cent of its customers – or around 700,000 people – could lose gas supply before the situation is resolved.

Doug Stout, vice-president of market development and external relations for the utility, urged customers to use natural gas sparingly in the meantime.

"We'd like you to turn your thermostat down as low as possible," Stout said. "Reduce the amount of gas you use as much as possible in your home and business as we work through assessing what's going to happen to the system."

Stout suggested customers limit the use of their fireplaces, barbecues and even hot water. But conserving natural gas is a tall order for restaurants, where the majority is used for food preparation.

FortisBC has natural gas storage facilities in the Lower Mainland and on Vancouver Island that will help supply the system during the pipeline shutdown, and there is another pipeline from Alberta to southeast B.C. that's still flowing.

Unfortunately, the Enbridge pipeline that exploded and the second that was turned off as a precaution supply about 85 per cent of the natural gas used in B.C., Stout said.

And almost 24 hours after the explosion, it remains unclear how long it could take to get the pipelines up and running again.

"We recognize the impact this will have on customers," Enbridge said in a statement. "At this time we cannot speculate about how long it will take to resolve the situation. We appreciate everyone’s patience as we continue to work safely and in a manner that minimizes the interruption of gas supply to communities."

FortisBC told CTV News it's working to bring in extra gas through the TransCanada line, and by activating its Tilbury and Mt. Hayes liquefied natural gas plants.

Tuesday’s explosion happened around 5:45 p.m. near the rural community of Shelley, about 20 kilometres northeast of Prince George, sending a bright orange fireball into the sky.

Nobody was hurt, but about 100 people in the Lheidli T'enneh First Nation had to be evacuated as a precaution. Almost every resident was able to return home late Tuesday night.

Witnesses from the Lheidli T'enneh Nation told CTV News they both heard and felt the impact of the blast from their homes.

"My whole house shook," Phyllis Seymour said. "I thought it was just a big thunder (strike)."

Some residents expressed concerns for their safety, though Enbridge has stressed that protecting the public is its top priority. The company also confirmed the fire that broke out Tuesday has been extinguished.

"Enbridge is working in co-ordination with area first responders, communities, officials with the federal, provincial and local governments, and regulators to ensure the safety of area residents near the impacted zone," it said.

B.C.'s Ministry of Environment said the incident involved a 900 PSI gas line, but few other details about what happened – including the cause of the rupture – have been confirmed. The province is investigating alongside the Transportation Safety Board and National Energy Board.

With files from CTV Vancouver's Breanna Karstens-Smith