Derbyshire Constabulary confirmed last night that four bodies were found in a house in Chandos Crescent, Killamarsh, early on Sunday morning.
Chief Constable of Derbyshire Rachel Swann identified the victims as Terri Harris; her two children, 11-year-old daughter Lacey Bennet and 13-year-old son John Paul Bennett; and Lacey's friend Connie Gent, also 11, from Sheffield.
A fundraiser has now been set up in their memory, with more than £11,000 raised in just 16 hours.
The fundraiser was set up by Cassie Perry, believed to be a friend to the siblings' father, Jason Bennett.
Tributes paid to mum Terri Harris after man is arrested on suspicion of murdering her and three children in Killamarsh
Cassie wrote: "I'm starting a fundraiser to help Jason Bennett at this devastating time.
"For those who may not have heard this tragic news, Jason's two little angels, Lacey and John, and their mother, Terri and friend were all taken from him yesterday.
"The alleged person responsible is currently being held.
"Can we all pull together to ensure Jason is overwhelmed with support and love at this hugely difficult time?
"If for any reason you are not able to donate, please please please show your support in other ways by sharing this fundraiser so we can gain as much support as possible.
"Any additional funds above the cost of their funerals will be given to his family and his friends family also.”
Jason visited the crime scene earlier today, where he was consoled and hugged after breaking down in tears close to the spot where floral tributes have been left.
To donate, please go here.