A safety investigation is being carried out by the B.C. Oil and Gas Commission after a dangerous sour gas leak from an EnCana pipeline forced about 15 northeastern B.C. residents to flee their homes on Sunday.

EnCana has yet to say what caused the leak at a well located about 10 kilometres south of Pouce Coupe, but officials have confirmed it was not caused by sabotage.

Several residents of the nearby Tomslake area told CBC News they fled their homes after a large plume of sour gas moved in Sunday morning.

"I was scared, but I wasn't panicking," said Kerry Klemmer, who lives just half a mile from the well that leaked.

"There was just the high pressure noise … like a jet plane ready to take off," said Klemmer.

Other residents smelled rotten eggs and felt their eyes and noses burn, tell-tale signs of the toxic sour gas. One man drove door-to-door alerting people as a huge gas cloud rolled in.

"Someone else called us and said, 'Okay we're all getting out of here,'" said Klemmer, "And because of having had some bombings in the area ... everyone was concerned."

About 15 people were evacuated to a local community centre for several hours while the leak was repaired, before they were able to return home around 1 p.m. MT

Investigations launched

On Thursday, Encana spokesperson Carol Howes confirmed the leak was from a company pipeline, and said the cause is still under investigation.

The B.C. Oil and Gas Commission will look at the root cause of the failure and leak and consider whether the alarm system and evacuation procedures are adequate, according to commission spokesman Steve Simmons.

"This is fairly uncommon," said Simmons, "I think it had the potential to be serious."

Simons said it was fortunate the sour gas that leaked had a low level of toxicity.

"The leak was sour gas, but only 0.5 per cent sour gas — not a dangerous amount," he said.

But Simons did confirm the gas can be flammable and explosive — a concern in an area where some homes are heated by wood.

Delayed alarm raises concerns

Officials are also investigating reports the leak began hours before EnCana's alarms were triggered.

One person reportedly smelled the gas around 4 a.m. MT, about five hours before the alarm was raised by EnCana at 9:15 a.m.

EnCana maintains the site was immediately secured and the gas shut off as soon as the leak was detected.

"The safety mechanisms are in place," said Howes. "EnCana did everything in terms of addressing that situation immediately."

Simmon said he is concerned residents didn't contact the commission and part of the investigation will look at "why nobody called us."

He also expressed concern that local residents decided on their own to evacuate their homes, saying they could have driven into danger.

Locals scared to speak out

CBC News contacted several people who fled their homes, but many were reluctant to be interviewed, fearing their jobs in the local oil and gas industry, which is dominated by EnCana, could be jeopardized.

Others expressed concern that speaking publicly might draw unwanted attention from RCMP investigators, who have been criticized for being heavy-handed in their investigation of the six unsolved bombings at EnCana wells in the area over the past year and half.

Simmons acknowledged the recent bomb attacks, along with two threatening letters sent to local newspapers, have made sour gas leaks a sensitive issue.

"In this area in particular, there's still a great deal of anxiety given the criminal activities that have taken place over the last year. So there is a great deal of sensitivity," said Simmons.

Sour gas is a term used to describe natural gas containing hydrogen sulphide, a toxic, flammable substance.

With files from Betsy Trumpener