Two more families have been displaced following another overnight fire in the Comox Valley.

Firefighters were called to a blaze at a duplex in Oyster River around 10:30 p.m. Monday and arrived to flames shooting out of the building.

Crews eventually put out the flames and investigators performed two separate checks of the property after the blaze was believed to have been extinguished.

There were no signs of smoke or flame during the checks, the fire department said. But to their surprise, the fire flared up again and crews were paged back to the building just after 3 a.m., an hour after the second check.

"When I arrived here, the whole roof from one end to the other end was fully involved," said Oyster River Deputy Fire Chief Bruce Green.

Crews spent the remainder of the night extinguishing the blaze once more. The interior of the structure appeared to completely destroyed.

A family of four and a family of three were displaced but all made it out uninjured, according to Green.

The family of three was taken to hospital to get checked out for possible smoke inhalation, and Emergency Social Service found accommodations for those affected.

Green said unattended candles are believed to have sparked the original fire, but it's still unclear how it flared back up.

"Hindsight's 20-20. We're still going to do an investigation now to determine what caused the flare-up. We're unsure at this time why it rekindled," he said. "I'm sick to my stomach right now because I feel bad, guilty, that we didn't do our job, I didn't do my job, that this happened."

The daughter of the building's landlord praised the fire department for doing everything they could.

"One side, as of last night, we thought was fine," said Elizabeth Kuss. "I just want it to be known that these firemen went out of their way to save this house. My hat's off to them."

Kuss said she's confident the community in Oyster River will step up to support the families displaced and provide them with anything they need.

It's the second major house fire in the Comox Valley in the last week. On Saturday, flames ripped through three homes in Cumberland, leaving one senior dead and several people displaced.