07/31/2013 12:09 EDT | Updated 09/30/2013 05:12 EDT

'Call before you dig' didn't work in Quesnel, company says

FortisBC said that inaccurate maps are to blame for the major gas leak that was triggered by a contractor's digging in the northern B.C. city of Quesnel on Monday afternoon.

Twelve blocks in had to be evacuated after a natural gas main was hit at a construction site near the Safeway in downtown Quesnel at around 3 p.m. PT.

Homes, a seniors' residence, and businesses were all evacuated while FortisBC crews worked to bring the leak under control.

A scheduled city council meeting was also cancelled, but Mayor Mary Sjostrom didn't blame the workers who hit the gas line — she said the contractor did what he was supposed to, and followed the "call before you dig" safety guideline.

FortisBC says the contractor is not to blame for the emergency.

Joyce Wagenaar, spokeswoman for FortisBC, says the utility didn't even know the pipe existed.

"This was a very rare incident where we had a piece of abandoned pipe. A small 1½ inch line that was not marked on the map that was provided to them," she said.

Wagenaar said technicians now think the mystery pipe was installed sometime in the 1950s.

No one was injured in Monday's incident, but residents of Quesnel are very wary of gas leaks already: In 1997, six people were killed and 20 were injured after a severed gas line caused an explosion at a thrift store.