Four people were reportedly stabbed to death at a home in Delaford Road, Bermondsey, in south-east London, with police officers receiving the first reports of disturbances at around 01.40 British Standard Time on Monday, 25 April.
The victims, according to a BBC report, are three women and one man.
Emergency medical workers pronounced them dead as soon as they reached the scene.
One man has been arrested on suspicion of murder. He is presently in custody at police station in south London.
The police are saying that all the five people knew each other. Officers also said that the next of kin were being approached.
The road has been blocked off from the middle with metal fencing. Some white forensic tents have also been put up for the investigation.
London Mayor Sadiq Khan tweeted about the murders.
"Heartbroken to hear that three women and a man were killed last night in a devastating incident at an address in Southwark. My thoughts are with the family & friends of those who have lost loved ones in this awful crime," he wrote.
Local MP Harriet Harman also tweeted about the incident, calling it "tragic".
She also wrote that she was "liaising" with Southwark Police and Southwark Council.
(With inputs from BBC.)
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