Los Angeles, CA- A mother and grandmother who used an oven to try to keep warm in the cold overnight temperatures were found dead Saturday, both victims of carbon monoxide poisoning.

Los Angeles County deputies say just before 2:00 p.m. they responded to a call in the 2200 block of El Segundo Blvd in Willowbrook. The call came from a woman who went to check on her mother and grandmother. Upon entering their home, she smelled the strong odor of gas and found the oven on and the oven door open.

The woman closed the oven door and called 9-1-1.

Los Angeles County fire crews entered the home and detected “extremely high levels of carbon monoxide gas” within the residence. They discovered the victims inside the home — they were pronounced dead at the scene.

The victims have been identified as 62 year old Yvonne Hopson and her mother, 81 year old Doris Jean Hopson.

Carbon monoxide poisoning is the leading cause of accidental poisoning death in the United States – each year, it kills than 400 people, more than 20,000 visit the emergency room and more than 4,000 are hospitalized, according to Centers for Disease Control and Prevention.

People who are sleeping or intoxicated can die from carbon monoxide poisoning before ever experiencing symptoms.

CDC officials say the fatalities are highest among Americans age 65 and older.