A mum and her eight-year-old daughter have died after running a car in the garage to try and keep warm in severe weather.
Police in Houston, Texas, were carrying out a welfare check at an address on Tuesday where they found a family of four suffering from carbon monoxide poisoning.
More than 1 million people lost power in Houston as demand for electricity soared during the coldest night in 32 years.
The two females were pronounced dead at the scene and a man and a seven-year-old boy were rushed to hospital.
Art Acevedo, chief of Houston Police, said in a statement: “This is heartbreaking.
“Initial indications are that [a] car was running in the attached garage to create heat as the power is out.
“Cars, grills and generators should not be used in or near a building.”
“Please bundle up and be aware of the extreme danger carbon monoxide poses for us. Praying for this family.”
Police have also warn that sitting in a running car outdoors to stay warm can pose a carbon monoxide danger, if the tailpipe is blocked by snow.
Carbon monoxide is an odourless, colourless gas that is in fumes produced in cars, engines, stoves, lanterns, grills, fireplaces, gas ranges or furnaces.
Symptoms of carbon monoxide poisoning are often described as “flu-like” and it can kill people in their sleep before they show signs.
In a separate tragedy in Houston on Tuesday, a grandmother and her three young grandchildren died in a house fire .