A seven-year-old boy has died in hospital after being taken unwell along with two adults, police have said.
Officers were called at around 3.30am today to Thameside in Chertsey, Surrey, at the request of the ambulance service.
The people inside the property had fallen ill and were taken by ambulance to hospital, a spokesman for Surrey Police said.
The boy was later declared dead. A man in his 40s, believed to be his father, and a woman in her 30s, who is understood to be his mother, are in a serious condition but it is not thought to be life threatening.
Fifteen people, including police officers, were taken to hospital as a precaution. One person who showed signs of illness has now been released from hospital.
Nearby properties were evacuated as a precaution and people from homes close by were advised to go to hospital to be checked as a precaution.
Chief Superintendent Dave Miller said the cause of the illness was unknown amid speculation that carbon monoxide poisoning may have been to blame.
He said: “It is very sad that a young child has died earlier today. Our thoughts are with his parents who are currently ill in hospital.
“Police officers are currently with them and we will continue to offer our support during this difficult time .
“Our aim is to keep people safe and find out the cause.
“I would like to reassure local residents our officers are working closely with partner agencies and a full and thorough investigation is currently under way to determine the circumstances around this tragic incident.
“We are currently following various lines of inquiry and it would be wrong to speculate on the cause of death at this stage.
“The cause of the illness is currently unknown but what I can confirm is that the people who were taken ill are from a very localised area.
“We cannot rule out that there may be a link to flooding in the local area and whilst the investigation is ongoing local residents should follow sensible precautions.”