A street cleaner who tried to stop a burglar making a getaway has died after being stabbed in the torso.
The eastern European man, aged 40, died in St Mary's Hospital, Paddington, Scotland Yard said.
Police said they were called to an assault in Rylett Road, west London, just before 2pm on Wednesday and found the man with a stab wound to the torso.
Six people have been arrested in connection with the incident.
A 30-year-old man was arrested on suspicion of murder and is currently in custody at a central London police station.
Two other men and three women have all been arrested on suspicion of assisting an offender.
Although police believe they know the dead man's identity, they are awaiting formal identification.
A post-mortem examination date and venue are to be arranged, police said.