Police rushed to the venue on Uxbridge Road, Ealing, just before midnight. The victim, believed to be in his 50s, was pronounced dead at the scene.
Scotland Yard said detectives were looking for witnesses as they widen a probe into the shocking attack. No arrests have been made yet but the force say a murder investigation has been launched.
The man’s family have been informed and will be supported by specialist officers. Witnesses are urged to contact police on 101, referencing 8656/23jul.
You can also call Crimestoppers on 0800 555 111 if you wish to provide information anonymously.