A fire decimated a homeless camp in the Fraser Valley overnight as temperatures dropped well below zero across the region.

The blaze broke out after dark Wednesday at a camp on Railway Avenue in Chilliwack, under the Yale Road overpass.

Homeless advocates said one of the residents had been keeping a propane tank and heater inside the tent where the fire started, and the flames quickly spread throughout the camp.

Video that was taken by a passerby and uploaded to Facebook shows people standing outside several tents as the fire rages just metres away.

Bill Raddatz of the Ruth and Naiomi's Mission shelter said they have room for people who need a place to keep warm overnight, but that some homeless residents, for sometimes complicated reasons relating to their mental health, decline their offer.

"We have street outreach workers to encourage them to get inside," Raddatz said, noting there are three shelters with more than 100 beds available in the city.

"It's sad to say, it's sad commentary, but it's by their own choice that they're here… All three of us, our policy is no one's turned away."

Fortunately, there were no injuries during Wednesday's fire, but most of the camp was destroyed and officials forced all residents to evacuate for safety.

Over the weekend, advocates said a homeless woman suffocated to death when her tent collapsed onto her under the weight of snow.

Environment Canada is forecasting temperatures of -8C overnight Thursday in Metro Vancouver, and that things will be much worse in the Fraser Valley.

There’s an ongoing warning stemming from the bitterly cold air blowing in from an arctic ridge of high pressure over the B.C. Interior, and wind chill values nearly -20C are expected in the valley at night.

People who are going outside are advised to dress warmly in layers, stay dry and cover as much exposed skin as possible to avoid frostbite.