Detectives are not looking for any more suspects in the investigation into four people - who were stabbed to death at home in South Bermondsey.
A man, in his late 20s, has been arrested on suspicion of murder, and remains in custody.
Officers found him at a residential property in Delaford Road, Southwark, at around 1.40am this morning, along with three dying women and a man.
Despite the efforts of police and paramedics, the four victims died at the scene.
Southwark Borough Commander Ch Supt Colin Wingrove confirmed that detectives were not looking for any once else in relation to the deaths at this stage.
He said: “In the early hours of this morning, following a call from neighbours, officers forced entry into a house here in Delaford Road.
“Inside the house they [detectives] made a dreadful discovery of four people who had been stabbed.
“Despite the best efforts of officers and paramedics, all four people were sadly pronounced dead at the scene.”
The senior officer told a press conference - outside the crime scene - that the three female victims were believed to be in their mid 60s, mid 40s and mid 30s, and the male victim was in his mid 60s.
“I want to offer my heartfelt condolences to the family and friends of all those concerned,” he said,
“This is a deeply shocking incident and we will do everything we can to provide support to everyone affected at this difficult time.
“A man in his late 20s was arrested at the address on suspicion of murder, and he is currently in custody.
“At this early stage we are not looking for any other person.
“We believe all those involved may have been known to each other.”
Ch Supt Wingrove described it as a “terrible incident” and confirmed more police officers would be patrolling around South Bermondsey in the coming days.
Scotland Yard’s Murder Squad has launched an investigation, and the Southwark Borough Commander urged anyone with information to contact the police.
He said: “Such terrible events are rare, but this will not diminish the shock that was felt across London and beyond, and I can assure you that this investigation will be thorough to ensure justice for victims, their families and the community. “
One neighbour said that the victims were all part of the same family.
The neighbour, 55, told LondonWorld that he had heard screams coming from the house in the middle of the night.
He said: “Roughly around 1.30am I heard some screaming.
“It sounded like someone was getting battered, having a fight or getting beaten.
“I opened the window and didn’t see anything.
“I was dozing off again and then I heard the helicopters.
“When I opened the windows again I saw loads of police cars, four ambulances, helicopters hovering around.
“There were a lot of armed police here.
“It’s unsettling, unnerving - a very barbaric act.”