A 27-year-old woman has been arrested following a South London house fire that killed four children on Thursday.

Last night a 27-year-old reportedly left two sets of twins, aged four and three, at home alone when a fire broke out. The woman has been arrested and held in custody under suspicion of child neglect, following the deaths of the four children.

Richard Mills of the London Fire Brigade confirmed this, saying in comments reported by Sky News: “On arrival there were four children in the house.”

The cause of the fire was “unknown”, but the fire brigade stated that the blaze was “very well-developed” by the time they arrived at around 7pm on Thursday evening.

All four boys were carried out of the house by firefighters and were given emergency medical attention including CPR, before being taken to two hospitals in South London, where they tragically died.

The London Fire Brigade said emergency crews including around 60 firefighters and eight fire engines were sent to the property.

The fire was reported to be “under control” by 8.36pm.

A wreath bearing the names “Kyson, Bryson, Leyton and Logan” signed “Grandad” was left outside the home.

It has been confirmed that the children were all related.

London Fire Commissioner Andy Roe said: “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.”

The Fire Commissioner has said that the crews who attended the scene would be offered counselling.

A neighbour suggested that she previously had no concerns about the welfare of the children, describing them as “cute” and saying: “The kids looked really happy. The boys looked really sweet and nothing seemed out of order.”

The Crown Prosecution Service’s definition of child abuse includes neglect, where “someone may abuse or neglect a child or young person by inflicting harm, or by failing to prevent harm”. A child in this instance is defined as anyone under the age of 18.

The maximum penalty in Britain for neglect is ten years.