A bus driver was taken to hospital with head injuries after he was attacked with a bicycle D-lock.
The 41-year-old man was walking through the concourse of Golders Green bus station when he was attacked on Tuesday morning.
Witnesses saw a man approach the victim and hit him on the head with the lock before fleeing on a mountain bike.
The incident happened at around 10.30am in the Golders Green Road bus station.
The victim was taken to a north-west London hospital, and his injuries were still being assessed on Tuesday afternoon.
The suspect is described as a black man, of small build, who was wearing dark clothing.
Police are appealing for information following the assault.
Anyone with information should call police on 101 or Crimestoppers anonymously on 0800 555 111.
