Someone deliberately set the explosion that damaged another EnCana gas pipeline in northeastern B.C. early Wednesday morning, RCMP investigators say.

According to the RCMP's Integrated National Security Enforcement Team, the blast was the fifth in a series of criminally motivated acts at EnCana sites in northeastern B.C. since October.

As of noon Thursday, EnCana was still working to contain the leak at the wellhead site near Pouce Coupe. Once the leak is contained, a full forensic examination will be started by the same special RCMP unit that investigated the four previous bombings, Cpl. Dan Moskaluk said.

The explosion was discovered by EnCana employees after they detected a sudden drop in pressure in a sweet gas pipeline on Wednesday and traced the source of the leak to remote wellhead about eight kilometres south of Dawson Creek.

EnCana spokeswoman Rhona DelFrari said the area around the leak was cordoned off and there is no threat to the public or the environment, but it's alarming nonetheless.

"If it was caused by an explosion that was set on purpose, then that is very frustrating to us because it causes a potential risk to the public and our staff in the area," she said.

Fortunately, no residents were in the vicinity and no one was at risk, DelFrari said.

Investigators believe the bomber in the four previous incidents was a local resident with a grudge against EnCana, which operates a large network of sour gas wells in the area. However, the latest incident appears to involve a pipeline that carries sweet gas, not sour gas.

Sour gas is a type of natural gas that contains toxic hydrogen sulfide. Sweet gas does not contain significant levels of the compound.