Three Ramona residents were transported to the hospital Thursday morning with carbon monoxide poisoning, according to the County News Center.
Starting at about 9:30 a.m. Thursday, medics were sent to a home on Highway 78 for a person who was possibly "cardiac in nature," the county's statement read.
Shortly after, a person in the same home became sick, called 911 and then became unresponsive to dispatchers.
When authorities arrived, they found two people outside the house with an altered level of consciousness. A third person was found collapsed inside the home.
The three patients were taken to the hospital and are expected to be okay.
County officials who tested the home's air found high levels of carbon monoxide. The residents did have a carbon monoxide detector, but it was out of batteries.
The officials believe the poisoning may have been the result of the home's heating and air conditioning exhaust vents, which was clogged with acorns and debris.
"As we get into the winter months, it’s more critical than ever to make sure your heater is in good working order," said Capt. Brent Stephens of Intermountain Fire/County Fire Authority in the statement. “Also, make sure your home has a carbon monoxide detector and check the batteries.”
Click here for tips on how to safely heat your house in the winter.