A woman has been arrested on suspicion of child neglect after two sets of twin boys, aged three and four, died in a house fire in south London.
The four children, who are believed to be related to each other, perished inside a mid-terrace house in Collingwood Road, Sutton, on Thursday evening after an "intense blaze" broke out.
The Metropolitan Police said they had arrested a 27-year-old woman on suspicion of child neglect.
Jason Hoath posted on Facebook that the boys were his "amazing smart and beautiful grandsons" Kyson, Bryson, Leyton and Logan.
He said they had been "taken too soon" and would "always be in our hearts and thoughts". He signed it =: "Boys I love you forever."
Firefighters arrived at the scene shortly before 7pm and entered the burning building wearing breathing apparatus. After removing the children they administered CPR but the all four were pronounced dead shortly after.
The fire was under control by 8.36pm and the cause is under investigation.
On Friday morning neighbours were seen leaving bouquets of flowers at the scene of the tragedy.
Richard Mills, London Fire Brigade's deputy commissioner, said when firefighters arrived at the house, the blaze was “very well-developed” and only the children were inside.
“I can confirm that they are two sets of twins, ages four and ages three," he told reporters at the scene.
Asked if anyone else was in the home, he said: “On arrival there were four children in the house.”
He also confirmed the victims were all boys.
On the impact of the incident on fire crews, he said: “It’s a very traumatic event.
“They (firefighters) attended a very well-developed fire; they got there in under three minutes.
“Entering a building and rescuing life is always a very difficult place to be. The age of the children, the fact they are so young will have a profound impact on them.”
London Fire Commissioner Andy Roe said their deaths had “left everyone numb with profound sadness”.
“This is an incident that has left everyone numb with profound sadness. My thoughts are with the family and friends of the children, the whole local community and all those who will be affected by this fire," said Mr Roe.
“Fire crews arrived quickly and located the children inside the property.
“They were brought out of the house and given immediate emergency care.
“The welfare of our staff involved in this incident is very important to us and all of them will be offered counselling as a priority.”
The London Fire Brigade said eight fire engines and around 60 firefighters were called to the scene at just before 7pm.
The Metropolitan Police said the children’s next of kin had been informed and would be provided with specialist support.
“The thoughts of everyone at the South Area Command Unit are with the family and friends of these four young children, who have suffered such a devastating and tragic loss tonight," said Superintendent Rob Shepherd.
“I know these sentiments will be shared by the local community, Sutton and London as a whole.
“We remain on scene with our emergency service colleagues and will be working through the night and beyond. At this very early stage the cause of the fire is unknown and will be investigated.”
"We sent a number of resources to the scene including ambulance crews, advanced paramedics, paramedics in fast response cars, incident response officers and members of our Hazardous Area Response Team (HART)," said Graham Norton, assistant director of operations at London Ambulance Service.
“We also dispatched trauma teams from London’s Air Ambulance and Air Ambulance Kent Surrey Sussex – both teams consisted of a paramedic and a doctor in a car.
“We treated four children at the scene and took them to hospital.
“Our thoughts are with the family and friends of the four young children and everyone affected by this devastating tragedy."