It's left a quiet community shaken and a doting dad "heartbroken".
Four bodies were discovered at an address in the Derbyshire town of Killamarsh yesterday (Sunday, September 19) at about 7.25am after police were called "in relation to concerns for the safety of a man from the area".
Three of those who died were children – a brother and sister, along with a friend. The fourth person was a woman.
Read more: Distraught dad in tears at scene of four deaths in Killamarsh
The four have since been named as 35-year-old Terri Harris, her two children - 11-year-old daughter Lacey Bennett and 13-year-old son John Paul Bennett - and Lacey’s school mate Connie Gent, also 11, from Sheffield.
A murder inquiry has been launched, and one man - a 31-year-old from Killamarsh, who was known to the family - is in custody.
Jason Bennett, who is understood to be the father of two of the children found at the house, described his son John and daughter Lacey as his "angels".
Devastated Mr Bennett, who is believed to have been on holiday in Devon at the time the tragic news broke, shared on Facebook how he'd found out the pair "had been taken away" from him.
"Life will never be the same. My angels. Won't be long till I'm touching your cheeks, holding you close and kissing your beautiful faces. Only you two can fix me," he wrote.
"Absolutely heartbroken. I didn't protect my beautiful babies enough and now they have been suddenly taken away from me."
Having made the agonising four-hour drive home knowing his son and daughter were gone, he broke down as he laid flowers at the address on Monday morning.
The card which accompanied them read: "To Lacey, my beautiful Tick Tock Queen, look after your brother and don’t wind him up. Soon I will be there to kiss you, hold you tight and make it all better. Love, Daddy."
A bouquet left for John read: "To John, my beautiful son. Keep your kind heart shining while the angels are looking after you for me.
"I will see you soon. Daddy loves you. Fly high, so proud of everything you achieved."
The children's grandparents, Debbie and Trevor Bennett, also arrived at the scene to leave flowers.
John and Lacey's mum Terri, along with Connie Gent, who was staying over at their home for a sleepover, were also among those who lost their lives at the property.
Charlie Gent, believed to be Connie's father, posted on social media: "My little girl has gone, I can't even put into words or even how to feel or react right now.
"Fly safe baby girl, I love you with all my heart and always will. Gonna miss you like crazy."
Speaking at the scene earlier, Chief Constable Rachel Swann said a team of detectives had been working through the night to understand the circumstances that led to their deaths and she urged anyone with any information to come forward.
She also praised the work of her officers and the East Midlands Ambulance Service staff who attended the incident, stressing that "the force did not have any prior contact with those involved".
Meanwhile, the Outwood Academy City school in Sheffield confirmed it was closed today following the "tragic incident" involving three of its students.
In a statement on Twitter, the school said: "It is with great sadness that the academy will be closed today.
"A tragic incident has taken place in the community involving three of our students. We will however be open to any students who need our support.
"Our thoughts are with all those affected by this sad news."
Hundreds of people gathered in the town of Killamarsh overnight to hold a nearby candlelit vigil in memory of the victims and show their support for Mr Bennett.
A fundraiser has also been launched to raise money for the family of the Killamarsh sleepover tragedy's four victims.
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