Two people have been stabbed to death and four others hurt in separate attacks in the early hours of the morning in London.
A man died after being stabbed outside a private party in Park Lane, in the West End, at about 05:30 GMT.
Two men, aged 37 and 29, and a woman, aged 29, were also stabbed.
About an hour earlier, a woman was fatally stabbed in Southwark and at around the same time a woman was shot at a nightclub in Hackney.
Police said the man who died at the Park Lane party appeared to be a member of security staff, as were the other two men who were hurt.
The men and the woman were treated at the scene before being taken to hospital. They are not thought to have life-threatening injuries.
Detectives have launched a murder investigation and are in the process of informing the man's next-of-kin. A post-mortem examination is due to be held later.
Det Ch Insp Andy Partridge said: "The incident took place outside a venue that was hosting a private party.
"It appears the deceased and the two injured males were working as security staff for the party, they were attacked by a group of males who were outside trying to enter the venue.
"The female was also attacked as she assisted the security staff in closing the front door of the premises."
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In the Southwark attack, police were called by paramedics to an address in John Ruskin Street, Camberwell, at 04:20.
A woman, aged in her early 30s, was found with stab wounds and, despite the efforts of paramedics to save her, she was pronounced dead at 04:50.
She has not been formally identified and her next-of-kin have not yet been informed.
A man, 34, was arrested at the scene on suspicion of attempted murder. He has been taken to a south London police station where he remains in custody.