An elderly couple and their daughter have died of suspected carbon monoxide poisoning in a caravan in Cornwall.
Pensioners Alfred and Audrey Cook, aged 90 and 86, and their daughter Maureen, who was in her 40s, were found dead with their pet dog on Saturday 23 February after they failed to answer the door of their static caravan to their carer.
Police and a specialist hazardous materials adviser were called to the incident in Tremarle Home Park in North Roskear, Camborne.
Inspector David Eldridge, of Devon and Cornwall Police, said: "We were able to see that there was a figure sitting in a chair, but the occupants were unresponsive to knocks at the door.
"Cornwall fire and rescue were called. They forced entry into the property and found that the three people were all dead."
A spokesman for the fire and rescue service confirmed carbon monoxide poisoning was believed to have caused the deaths after the family turned on a heater to warm themselves in the freezing cold the night before.
Camborne town councillor David Bigg described the deaths as an "appalling tragedy".
"Tremarle Park is a residential caravan site and has provided homes for people for many years," he told The Observer. "It is a well established facility and it is very well run."
Police are investigating the incident.
Carbon monoxide poisoning from faulty heaters and dirty flues is believed responsible for 15 deaths in the UK every year, and is believed to have killed a woman in St Ives, Cornwall, earlier this month.
The gas is odourless, colourless, and tasteless. It is produced when carbon-based fuels, including gas, oil, wood and coal, do not burn completely, and inhalation can prevent blood transmitting oxygen to cells, organs and tissues. Inhalation over a prolonged period is fatal.