A man died when he was impaled on a large shard of glass after throwing a woman through a shop window in a street row.
The 30-year-old victim was seen arguing with the woman in the Regent Street area of London's West End shortly after 2am today.
Witnesses told police he hurled the woman against the window of a branch of Banana Republic up to three times.
After several blows, the glass shattered and the couple fell through, leaving the man fatally wounded.
Members of the public flagged down a police patrol who went to the shop, at the junction of Regent Street and Great Marlborough Street.
Paramedics also attended but the man was pronounced dead at the scene. A post-mortem examination will take place today.
The woman, also 30, was taken to hospital for treatment to multiple cuts, none of which was thought to be life-threatening.
A Metropolitan Police spokesman said: "Shortly before 2.15am, officers on patrol were informed by a member of the public of an altercation in Great Marlborough Street.
"When officers arrived at Great Marlborough Street, they found a male, believed to have gone through the window of a shop. A woman was also found at the scene, suffering cuts.
"London Ambulance Service attended but the man, aged 30, was pronounced dead at the scene.
"The woman, also aged 30, was taken to a central London hospital. Her injuries are not thought to be life-threatening.
"Officers believe they know who the deceased is but await formal identification and next of kin to be informed. A post-mortem examination will be arranged in due course."
Anyone with information should call Westminster Police on 020 7321 7434 or Crimestoppers, anonymously, on 0800 555 111.