Tests have revealed the amount of Carbon Monoxide recorded in a home where three people died was 20 times the fatal dose.
The bodies of John Cook, his wife Audrey and their daughter Maureen were found in a static home at the Tremarle Park in Camborne on Saturday.
Today Cornwall Fire and Rescue Service said they would have been 'unconscious within minutes'.
All homes at the park use gas for heating and cooking. Inspectors are examining the family's cooker.
Cornwall Fire Service is warning about the dangers of carbon monoxide poisoning after three people died at their caravan home in Camborne at the weekend.
John and Audrey Cook, their daughter Maureen and their pet dog, died within minutes - after inhaling fumes from a faulty heater.
Fire officers say having gas appliances checked every year and fitting a carbon monoxide alarm could save lives.
There are warnings about the dangers of carbon monoxide poisoning after three people died at their caravan home in Camborne at the weekend. It's thought they that John and Audrey Cook, their daughter Maureen and pet dog were killed by fumes from a faulty heater.
Fire officers say having gas appliances checked every year and fitting an carbon monoxide alarm could save lives. Watch John Andrew's report below.
Tributes have been paid to a family of three who all died of suspected carbon monoxide poisoning at a caravan park.
It's thought they that John and Audrey Cook, their daughter Maureen and pet dog were killed by fumes from a faulty heater. Fire officers say having gas appliances checked every year and fitting an carbon monoxide alarm could save lives.
– Sue Issacs, Neighbour
Everyone here is in total shock. You never think that something like this would happen on your own doorstep.
John, Audrey and Maureen were lovely people. It's so upsetting to think that three members of the same family have been wiped out in one go."
– Julie Boon, Friend of the family
I saw Maureen and her mum on Thursday morning when they were walking their dog.
Maureen asked about my dog and her mum commented on the cold weather and then they went. That's the last time I saw them.
They were a lovely family who loved their dog and their home. The whole community is shocked and devastated."
The family discovered dead at their static caravan home after suspected carbon monoxide poisoning have been named. They were 90 year old Alfred Cook, who was known as John, his wife, 86 year old Audrey Cook and their daughter, 46 year old Maureen. Their Jack Russell dog also died.
Camborne Town Council member David Biggs described the incident as an "appalling tragedy".
Tremarle Park is a residential caravan site and has provided homes for people for many years. It's a well established facility and is very well run. It was a shock to learn that three people have died there.
The woman was in her mid-40s. The age of her parents is not yet known. An investigation into what caused the deaths is under way, but the incident is not being treated as suspicious.
– Inspector David Eldridge of Devon and Cornwall Police
Shortly before 1pm this afternoon, 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 sat in a chair but they were unresponsive to knocks at the door.
Cornwall Fire and Rescue were called. They forced entry into the property and found that the three occupants were all dead.