The head of private school Epsom College has been found dead along with her husband and seven-year-old daughter in a property on school grounds.
Emma Pattison, 45, her husband George, 39, and their daughter Lettie were found dead at 01:10 GMT on Sunday.
Officers from Surrey Police said they were confident there was "no third-party involvement".
Epsom College said the community would be "coming together" to "process the news, grieve and pay our respects".
Det Ch Insp Kimball Edey said: "On behalf of Surrey Police, my team, and I, I first want to express my sincerest condolences to the friends and family of Emma, Lettie and George, as well as to the students and staff of Epsom College, for their tragic loss.
"I want to give my assurance that we will conduct a thorough investigation into what took place… and hope to be able to bring some peace in these traumatic circumstances. I would ask that their privacy is respected at this very difficult time."
Ms Pattison became Epsom's first female head only five months ago after six years as head teacher of Croydon High School in south London.
Her husband George was a chartered accountant who was director of a management consultancy firm called Tanglewood 2016, according to Companies House.
In December, Ms Pattison told a podcast run by students that her move had been "a really big change for my family", adding: "I've got a new job, my husband got a new job, which wasn't meant to happen, but did, and my daughter has started a new school."
Police officers remain at the scene and security guards in hi-vis clothing have been spotted at school entrances.
Pupils in uniform could be seen walking just inside the main gate of the school, where the flag is flying at half mast.
The grounds, near Epsom Downs racecourse, are made up of school buildings and residential properties.
In a tweet, the college said: "We hope everyone will respect the privacy of Emma's family at this time and allow the college's pupils, staff and wider community the time and space necessary to come to terms with this loss."
The school also confirmed it would be in close contact with Surrey Police.
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The chair of the board of governors at Epsom called his late colleague "a wonderful teacher, but most of all, a delightful person".
"On behalf of everyone at Epsom College, I want to convey our utter shock and disbelief at this tragic news," Dr Alastair Wells said.
"Our immediate thoughts and condolences are with Emma's family, friends and loved ones, and to the many pupils and colleagues whose lives she enriched throughout her distinguished career."
Croydon High School described Ms Pattison as "hugely respected and much loved".
"She was a warm, energetic, compassionate leader, dedicated teacher and generous, insightful colleague and friend," the school said.
A parent whose daughter attends Croydon High School said the news was "an utter shock and tragedy".
She told BBC News: "In her time as head teacher, she turned the school around, and she did so many things that enriched the children's lives.
"She was slight but very formidable, she knew all of the pupils by name. She was exactly what you would want from a head teacher."
Epsom has appointed Paul Williams as acting headmaster.
Local MP Chris Grayling said: "This is an appalling tragedy and my heart goes out to their family and friends and to everyone at Epsom College as well as at the little girl's school."
Surrey's Police and Crime Commissioner, Lisa Townsend, offered her "deepest sympathies", describing the incident as "awful".
"These events will no doubt have a profound and lasting impact on both the staff and students at the college and the wider local community," she said.
Insp Jon Vale, Epsom and Ewell's borough commander, said: "We're aware that this tragic incident will have caused concern and upset in the local community.
"While this is believed to be an isolated incident, in the coming days our local officers will remain in the area to offer reassurance to students, parents, teachers and the local community.
"I would like to thank the school and the community for their understanding and patience while the investigation continues."
Surrey Police added that the deaths had been reported to the coroner.
Boarding students at the college pay more than £42,000 a year, and its alumni include Conservative MP Sir Michael Fallon, broadcaster Jeremy Vine and his brother, the comedian Tim Vine.
The school, which both boys and girls attend, was founded in 1855 and describes itself as being consistently among the UK's leading schools, based on exam results.
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