An investigation into the deaths of an elderly couple and their daughter in Camborne is continuing today.
The man aged 86, his 90-year-old wife and their 46-year-old daughter were found dead yesterday from suspected carbon monoxide poisoning in their static caravan at Tremarle Home Park in North Roskear.
It is understood they may have been using a heater to keep warm as the region experienced freezing conditions overnight into the weekend.
The family's dog also died in the incident.
Firefighters, police and a specialist hazardous material adviser were called to the caravan on Saturday lunchtime after the family failed to respond to knocks on the door from the couple's helper who became worried.
Inspector David Eldridge of Devon and Cornwall Police, said: "Shortly before 1pm we were called to a caravan park near Camborne in Cornwall, where a helper had been unable to get a reply from an elderly couple who lived in the caravan.
"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 Cornwall Fire and Rescue Service confirmed carbon monoxide poisoning was believed to have caused the deaths.
Doreen Old, a resident at the caravan site, said: "I saw the fire engine go down first then saw the ambulance and then saw the police car. One of the neighbours said they had not seen any movement all morning. It's a tragedy."
Carbon monoxide is an odourless, colourless gas often dubbed the "silent killer" and has been the cause of a string of recent deaths in campsites and caravan parks.
Inhaling the fumes, which are caused by the incomplete burning of fuels, such as coal, wood, petrol and oil, prevents the red blood cells from being able to carry oxygen and can often be fatal.
Four people were taken to hospital suffering the effects of the gas at a house in Wellington, Somerset, last night.
Firefighters arrived at the scene after reports of a carbon monoxide alarm sounding.
One of the occupants was outside vomiting and all four people needed urgent medical attention.