105 Redwood Avenue

One side of duplex at 105 Redwood Avenue destroyed, while other side seriously damaged by fire. (Cathy Alex/CBC )

Investigators are trying to determine the cause of an overnight blaze that destroyed one side of a duplex and seriously damaged the other in the Northwood area of Thunder Bay.

Thunder Bay Fire Rescue said a call came in at 1:40 am Wednesday for a fire at 105 A Redwood Avenue.

When firefighters arrived both the first and second floors were burning.

Platoon Chief Dan Hyvarinen said firefighters initially attacked the blaze from the outside, but then moved inside to fight the fire that was spreading through the attic.

Hyvarinen said, "It was a difficult fire to fight. The entire structure suffered heavy damage due to the fire and fire fighting efforts."

That damage is now estimated at $300,000.  Thunder Bay Fire Rescue said initial reports show about 12 people escaped the fire without injury.

Fire officials said that working smoke alarms alerted the residents.  In a news release, Fire Chief John Hay said without them, the fire "could have had a much more tragic result."

Five pumpers and one aerial ladder truck responded to the fire, along with 22 firefighters.

Thunder Bay Fire Rescue and the fire marshal's office are investigating.