Tributes have been paid to a seven-year-old boy who died after falling ill in his flood-hit home.
Police are investigating whether flooding was a factor in the death of the boy, named locally as Zane Gbangbola.
Officers have refused to be drawn on whether carbon monoxide poisoning from a generator pumping out flood water from his home may have been to blame.
Zane's parents, Kye Gbangbola and Nicole Lawler, were also taken ill at the family home in Thameside in Chertsey, Surrey, just before 3.30am yesterday.
Two police officers and 13 nearby residents were released after being treated in hospital as a precaution.
As Zane's parents remained in a serious but not life-threatening condition at St Peter's Hospital, tributes were paid to the schoolboy.
Anoop Hothi, 31, taught Zane martial arts at the Sport Martial Arts Academy in Egham, which he joined aged five.
After a year, Zane became a member of the leadership team helping teach others new to the club, and last month he was promoted to green stripe belt.
Mr Hothi, also a neighbour of Zane's family, said: "Little Zane was an absolute joy to teach, and it's children like him who make teaching so much more rewarding.
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"I'm sure his school teachers would say the same thing. He was a lovely boy, and he came from good, caring parents.
"It's not the parents who are to blame for this. They were loving and caring people - it's the overall system that's to blame for his death.
"Zane had his whole life ahead of him. It's heart-breaking for his parents. I found out yesterday morning and I didn't want to believe it."
He added: "It was only a few months ago that my little brother was playing with Zane, and now he is in tears."
Mr Hothi criticised various agencies for their response to the floods in the area as he praised Zane's parents as the nicest neighbours he had ever had.
He said he saw some pipes coming out from the front of Zane's parents' property throwing out water, but he did not know whether a generator was being used.
Zane's mother is a member of the All Party Parliamentary Climate Change Group and his father is the founder of a sustainability consultancy.
A message on the Facebook page of Sport Martial Arts Academy announced Zane's death to members.
Part of it said: "Many of you will know him and his parents and many of the children would have trained with him over the last two years that he has been with us.
"Starting off in Little Samurais aged five, he was always enthusiastic and energetic about his training, showing the same passion for martial arts that his father has.
"After a year he was a member of our leadership team helping and teaching others new to the club. Just last month he was promoted to green stripe belt."
Chief Superintendent Dave Miller, of Surrey Police, said that the cause of Zane's death was still unknown.
It may take days for a cause of death to be established and it would be "inappropriate" to speculate on what it might be, he added.
There did not appear to be a wider risk to the public, with the illness limited to one family, Mr Miller went on.
Mr Miller said: "The investigation into yesterday's tragic death of the seven-year-old boy is ongoing and the cause of death is still unknown.
"We are continuing to work with partner agencies and officers are following various lines of enquiry.
"There have been no further casualties reported. This, coupled with expert advice, leads us to believe at this stage that this is an isolated incident localised to one family.
"Surrey Police will release an update when a cause of death has been determined, however this may take several days. In the meantime it would be inappropriate to speculate.
"Our thoughts continue to be very much with the boy's parents, who still remain in hospital, and we are continuing to support them during what is understandably a very difficult time."
Public Health England also said they do not believe there is a wider health risk to the public after nearby residents were evacuated and advised to go to hospital as a precaution.
A spokeswoman for the Department of Health agency, which is tasked with improving the nation's health, said it was helping police with their investigation.
"It is too early to speculate on the cause of death and Public Health England is working with the other agencies to assist this investigation and ensure appropriate action is taken to protect public health.
"Currently, there are no indications that there is a wider public health risk."
A South East Coast Ambulance spokeswoman said Zane was found to be in a "very serious condition" when crews arrived.
She said it was unclear what caused the illness and could not be drawn on the suggestions that carbon monoxide poisoning was to blame.
One local said he saw a yellow hose hanging from the ground-floor front window of the property where the family were taken ill.
IT worker David North, 45, who works in Chertsey, said: "I was taking photographs of the flooding in the local area. As I turned up, there was a higher-than-normal police presence.
"Officers were blocking direct access to some of the roads and they were being quite forceful about where you could and couldn't go.
"I saw a yellow hose coming from the front window on the ground floor. Whether it was pumping out water or something else, I don't know.
"My understanding is that this incident was found out while evacuations were being carried out due to the flooding."
A police scene guard remained at the location and road closures to Thameside were in place as the investigation continued.