A teenager has been stabbed to death and another is critically ill in hospital after a "highly worrying incident".
Scotland Yard said they found two males with stab wounds after being called to a disturbance around midnight involving a "large group of people" in Lichfield Road, Tower Hamlets, east London.
A murder investigation is now under way but no arrests have been made yet, say police.
The teenager who died, believed to be aged 17, was pronounced dead at 1.54am on Sunday.
The second man taken to hospital is thought to be 18.
Detective Chief Inspector Mark Rogers of the Met's Specialist Crime Command said: "This is a highly worrying incident that has left one young man dead and another fighting for his life in hospital.
"I am aware of reports saying that about a hundred people, armed with weapons were involved. This information does not appear to be wholly accurate.
"We know a significant number of people were caught up in this incident but not necessarily directly involved or armed with weapons."
The force said it has yet to arrest anyone in connection with the stabbings.
Anyone who has information that can help, including pictures or footage of the incident, is asked to call the Metropolitan Police major incident room on 020 8345 3715 quoting reference Operation Wildcast.
Alternatively, call Crimestoppers anonymously on 0800 555111.
Man shot dead in west London
The incident comes hours after a boy, believed to be 12, was stabbed in the east London borough of Newham.
Meanwhile, police have arrested a 29-year-old man on suspicion of murder following the death of a man in West Kensington in London.
Officers were called to Kensington High Street at about 2am on Sunday.
They found a man - believed to be in his 20s - with gunshot wounds and provided emergency first aid until the arrival of the London Ambulance Service and London's Air Ambulance.
The man was taken to a central London hospital where he later died.