Cold temperatures are always a cause for concern when it comes to house fires, as people try to stay warm.
The homeless community is also at greater risk, which is why one agency calls it "the killer cold."
It's warm inside the John 3:16 Mission in downtown Tulsa, but the cold hard truth is many homeless people refuse to come inside when the temperatures drop.
"The phrase for the homeless community is ‘killer cold,'" said Reverend Steve Whitaker. "We don't want anybody to get caught in killer cold out under a bridge somewhere, but the fact is, this year we have had some fatalities from people who got caught out in the weather."
Anything 40 degrees or below is considered killer cold. That's when the mission finds space for everyone who wants shelter and no space goes unclaimed.
"We have had it, when it's gotten very cold this year, actually filled up our lobby with people just sleeping on the benches, so it's been pretty full and pretty crowded," Whitaker said.
Cold weather causes a spike for another agency, too.
The Tulsa Fire Department has responded to more than 20 structure fires since Christmas Eve and half of those were weather-related.
"When the temperature drops, we start running on a lot more fires caused by heating equipment," said Captain Stan May.
May said those ten fires this week involved another method besides a gas or electric heating system.
"Fire places, space heaters, using the oven or the stove top to try and heat the house: those are all issues that are causing us a lot of problems right now," May said.
In Oklahoma City, a mother and her four children were killed in a house fire caused by a space heater.
TFD is stressing smoke detectors in the living room, hallways and near bedrooms.
Back at the mission, at least 150 people stay here at any given time. They go into overflow mode and can fit 100 more when the temperatures drop.
"We're very, very serious about making sure people get in out of the cold," Whitaker said.
The director of the John 3:16 Mission said three homeless people died in the last cold snap we had, and that was just the start of the extremely cold temperatures.