The head of Epsom College, together with her husband and seven-year-old daughter, were discovered dead in a residence on school grounds.
Emma Pattison, 45, her husband George, 39, and their seven-year-old daughter Lettie were discovered dead at 01:10 GMT on Sunday.
South East Coast Ambulance Service dispatched Surrey Police to the scene.
Police said they were certain it was an isolated event “with no third-party participation”.
An inquiry is underway to determine the circumstances behind their deaths.
“On behalf of Surrey Police, my colleagues, and I, I first want to extend my heartfelt sympathies to the friends and family of Emma, Lettie, and George, as well as the students and staff of Epsom College, for their awful loss,” Detective Chief Inspector Kimball Edey said.
“I want to provide my confidence that we will undertake a comprehensive inquiry into what took place last night, and hope to be able to bring some calm in these difficult circumstances. I would want to request that their privacy be respected during this difficult time.”
After six years as principal of Croydon High School in south London, Ms Pattison became Epsom’s first female headteacher in September 2022.
The institution charges more than £42,000 a year for boarding students, and its alumni include Conservative MP Sir Michael Fallon, broadcaster Jeremy Vine, and comedian Tim Vine.
According to Companies House, the head teacher’s husband George was a chartered accountant and the director of a management consultant business named Tanglewood 2016.
The chair of the board of governors at the school described his late colleague “a fantastic teacher, but most of all, a beautiful person”.
“I want to express our profound shock and dismay at this awful news on behalf of everyone at Epsom College,” Dr Alastair Wells stated.
“Our hearts go out to Emma’s family, friends, and loved ones, as well as the many students and colleagues whose lives she impacted over her long career.”
Ms Pattison’s kid attends Croydon High School, where Sheena formerly worked.
The mom, who only wished to provide her first name, said the news was “an complete shock and sadness”.
“During her term as head teacher, she turned the school around, and she did so many things that enhanced the children’s lives,” she told BBC News.
“She was small but quite threatening, she knew all of the pupils by name. She was everything you could desire in a principal.”
Epsom and Ewell borough commander Inspector Jon Vale stated: “We understand that this sad tragedy has created worry and uproar among the local community.
“While this appears to be an isolated event, our local police will remain in the area in the coming days to reassure children, parents, teachers, and the local community.
“I’d like to thank the school and the community for their patience and understanding while the inquiry is ongoing.”
The three fatalities, according to Surrey Police, have been submitted to the coroner.
