A man has been found stabbed to death on a bus in central London.
The 48-year-old was found fatally wounded on the 189 bus in Gloucester Place, near Dorset Square, at about 00:10 BST.
Detectives believe the man boarded the vehicle at Brent Cross bus station at 23:13 but are investigating when and where the stabbing took place.
The man was treated by paramedics but pronounced dead at the scene. No arrests have been made.
Scotland Yard said they believe they know the man's identity but are awaiting confirmation that his next of kin have been informed.
Det Ch Insp Noel McHugh said he wanted to "hear from anyone who was at Brent Cross bus station or who travelled on the 189 bus from Brent Cross towards the Marylebone area".
"It is crucial that we speak with any potential witnesses," he said.