RENO, Tex. (KXII) -- "It's colorless, it's odorless, it's tasteless, we could be breathing it right now and not even know it," said Reno fire chief Chad Graves.
Carbon monoxide is a silent killer, something a Reno family almost found out first hand Monday.
"They woke up in the morning, the parents weren't feeling well. They found their kids not feeling well as well, made the decision it's time to go to the hospital because something's going on," said Graves.
Firefighters found very high levels of carbon monoxide inside their home.
"Hot water heater, H-VAC system or furnace or stove or even a gas log fireplace. We have a chance of carbon monoxide if they're not burning like they're supposed to," said Graves.
Firefighters found gas had built up in an appliance.
They shut off the gas and fixed the problem..
The fire chief says they were lucky.
"Anytime we're burning anything like propane, natural gas, wood, anything that can basically create smoke and it's not burning real cleanly, that's when you get carbon monoxide," said Graves.
The Centers for Disease Control says more than 400 Americans die from unintentional Carbon Monoxide poisoning every year.
"Anytime we're doing something that's supposed to be done outside inside, obviously we have a chance of carbon monoxide poisoning," said Graves.
Firefighters say it's invisible but preventable.
"We need to have a carbon monoxide detector in the house and make sure it's working," said Graves.