Vandals have targeted another set of natural gas well sites in northeastern British Columbia, but authorities aren't immediately linking the latest attacks to three earlier bombings to EnCana pipelines in October.

Const. Jackelynn Passarell said Thursday valves were tampered with and shots were fired at well sites operated by Canadian Natural Resources Ltd. (TSX:CNQ) and Iteration Energy (TSX:ITX).

"Some unknown suspects entered the well sites and manually tampered with valves located on these well sites and also shot at structures on the well sites," Passarell said.

She said someone moved the valves from where an employee had placed them.

"At this point in the investigation we have no evidence to suggest that these are in any way linked to the recent targeted attacks on the EnCana well sites that are occurring south of us in the Dawson Creek area," she said.

RCMP describe the incidents as "mischief" and say the attacks appear to have happened up to one week ago on wells operated by the two Alberta-based exploration and resource extraction companies.

The well sites are located in a rural area called Osborn northeast of Fort St. John, not far from the B.C. Alberta border. There are no homes nearby.

Members of the Fort St. John serious crimes unit are now investigating.

Fort St. John is located roughly 75 kilometres away from Dawson Creek, the location of the last pipeline bombing.

Hundreds of large and small pipeline and well site construction companies have holdings within the city, and operate around the clock. Passarell says mischief is not uncommon, but this latest incident is being taken seriously because it involves several sites, she said.

"Any time a firearm is used to shoot at a gas structure obviously that could cause more significant damage so we are taking it very seriously."

Previous bombings

Three bombings in October aimed at Calgary-based energy giant EnCana's natural gas operations near Dawson Creek are still being investigated by RCMP.

Earlier this month, police identified and ruled out three people seen on a surveillance tape at a Shoppers Drug Mart postal outlet on Oct. 7 -- the same day a letter threatening the northern B.C. oil and gas sector was sent.

Sgt. Tim Shields said investigators believe EnCana was specifically targeted.

No one was injured in the blasts -- which occurred on Oct. 12, 16 and 31 -- but two pipelines were damaged and there was a small leak of toxic sour gas at a wellhead.

The blasts put a spotlight on local concerns over the rapid growth of the industry in the region, particularly projects containing sour gas.

The gas contains hydrogen sulphide, which can be lethal if breathed even in small amounts.

A booming industry

B.C. has more than 4,000 producing oil and gas wells, all in the northeastern part of the province, and the industry has seen massive expansion.

In 1996, it was worth about $370 million in revenues to the province. By 2006, that figure had jumped to $2.5 billion, mostly related to natural gas projects.

With files from The Canadian Press