A suspect was in custody Monday morning, and the police say they believe the attacker and the victims knew each other.
Three women and a man were fatally stabbed in the London borough of Southwark early Monday, the police said.
A suspect was arrested and is in custody, the police added.
The police say they believe that the attacker and the victims knew each other, but no information was immediately available on the circumstances surrounding the killings.
Officers responded to reports of a disturbance at 1:40 a.m. on Delaford Road in Southwark. After forcing entry, they found four people inside with what appeared to be stab wounds, the police said.
The four people were pronounced dead at the scene, the police added.
Though homicides are less common in Britain than in the United States, safety and policing remain major issues in London. There were 103 homicides in the city in 2021, 71 of which were committed with knives or sharp instruments, according to police statistics.