Detectives have been granted another 24 hours to question a 31-year-old man in connection with the murder of a mother and her two young children.
Naeemah Drammeh, aged one, and Fatimah Drammeh, three, died in hospital following a fire at their flat in Clifton, Nottingham in the early hours of Sunday.
Their mother Fatoumatta Hydara, 28, was also taken to hospital and placed on a life support machine, but sadly died on Tuesday morning.
A joint fire and police investigation concluded the fire at the flat in Fairisle Close, Clifton, was started deliberately and a triple murder inquiry was launched.
A man from Clifton, who was arrested on Sunday night, remains in custody while a team of 40 detectives continues to look at CCTV, forensics and other evidence, Nottinghamshire Police have confirmed.
The woman's husband Aboubacarr Drammeh - the father of the two children - was not in the UK at the time.
In an emotional tribute released on Wednesday, Mr Drammeh said it was "inconceivable to think who might have committed this cruel crime against my family".
He paid tribute to his "happy" and "bubbly" wife, and said "I will deeply miss my family".
Mr Drammeh, who flew back from the US after the fire, said: “It is with great sadness that we have lost Fatoumatta and our two daughters in such a tragic way.
“Fatoumatta had lived a short but a very beautiful and fulfilling life. A former voluntary worker, Fatoumatta was a very happy, bubbly woman who wouldn’t have the heart to hurt a fly.
“It is therefore inconceivable to think who might have committed this cruel crime against my family.
“We thank the Ahmadi Muslim community in Nottinghamshire, the Gambian community, the local neighbours and all those well-wishers for their continuous support in this difficult time.
“I and my in-laws are left without any daughters, grandchildren and nieces. I will deeply miss my family.”
'This is an horrendous crime that has broken a family'
Detective Chief Inspector Mark Sinski, who is leading the investigation, said: "The investigation is progressing well, and we won’t stop until we have got justice for the family.
"Officers have worked tirelessly since the early hours of Sunday morning building up a picture of what happened on that fateful day.
"This is an horrendous crime that has broken a family and had an immense impact on the Clifton community.
"I want to thank Clifton residents especially around Fairisle Close for their continued support as the investigation continues at the scene of this dreadful crime."