"TransCanada (TSX:TRP) has confirmed that its response personnel successfully isolated the pipeline break section that occurred earlier (Thursday) on our North Central Corridor system, and has now resumed delivery of natural gas to most of its industrial customers in the area," said spokesman Shawn Howard.
"TransCanada will be working with its remaining customers to restore full service."
Howard said a drop in pressure on the line, 140 kilometres west of Fort McMurray, was detected about 2:50 a.m. Thursday.
At least one oilsands producer in the area was affected by the leak. A Suncor spokeswoman said its operations have been slowed, but that it was too early to say by how much.
No public safety threat was expected from the leak in the 92-centimetre-wide pipe. It carries sweet gas, which is low in poisonous hydrogen sulphide.
The nearest residence is about 50 kilometres away. Although a work camp is a couple of kilometres from the site, it was not evacuated.
"Natural gas, particularly sweet natural gas, does tend to dissipate quite quickly into the atmosphere," said Rebecca Taylor, spokeswoman for the National Energy Board.
"You wouldn't see pooling of product on the ground."
First Nations in the area were notified of the leak, she added.
A spokesman for the Transportation Safety Board said the agency was aware of the leak and was following up with the company to gather more information. No decision had been made by Thursday afternoon to send investigators.
Howard said the cause of the line break is not yet known and will be determined during a subsequent investigation.
Energy board investigators were on site.
Also on HuffPost