VICTORIA -- Langford City Hall was evacuated Thursday morning for several hours after a report of an unusual smell in the building.

Langford Fire Rescue assistant fire prevention chief Lance Caven says crews figured out pretty quickly what the source of the smell was.

"We went and checked and we were getting some high carbon monoxide readings, or CO readings, in the building. So we decided to evacuate all the staff from City Hall, " said Caven.

The cause turned out to be a furnace that wasn't operating correctly, which was pushing carbon monoxide into the building.

"We called Fortis to assist us and we ended up sourcing out that it was the furnace for the building that wasn't operating correctly, and it was pushing CO into the ventilation system which is why we were getting the high reading," said Caven.

The assistant fire prevention chief says because carbon monoxide is odourless, tasteless, and you can't see it, it's known as "the silent killer."

He recommends that anyone with a gas-fired appliance or a wood stove ensure that they have a detector, and that it is working.