As cold temperatures move across the Rio Grande Valley, space heaters fly off the shelves. Fire safety professionals are reminding people to be smart about how they use them.

According to the Consumer Product Safety Commission, about 25,000 residential fires and more than 300 deaths in the United States annually are caused by something as simple as plugging a space heater into an extension cord.

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Cameron County Fire Marshal Juan Martinez said the safest way to use a space heater is to plug it directly into the wall. 

"Not everybody's got a plug on every single wall, and they typically want it to be as close to them as possible," Martinez said. "But we need to make sure they're doing it as safely as possible."

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With more than a quarter of Cameron County residents living under the poverty line, the issue is complicated. 

Martinez said he understands that for some people, staying warm means busting out the San Marcos blanket, but for others, the options are limited. 

"Chimeneas are for outside and outside only; same thing with barbecue pits," Martinez said. "It's easy for us to just say, 'We want to stay warm', so [we] use blankets and stuff like that. But there are some people out there that are so cold, that they don't really have a lot of options. So, they feel that their only option is to bring in something from the outside."

While the cold weather and possibility of snow is exciting for some, Martinez says it brings bad memories.

"I've been doing this for about 18 years," Martinez said. "And every time it gets cold, my number one fear is somebody perishing in a structure fire."