Scotland Yard has launched a murder investigation after an elderly man who had been riding a mobility scooter was stabbed to death in west London.
Police and paramedics were called to an address in Greenford after reports of a man had suffered stab injuries.
Doctors aboard the London Air Ambulance were also called to the scene.
Despite the efforts of medics, an elderly man, believed to be in his 80s, was pronounced dead at the scene.
Police say they are working to inform the man's family.
Detective Chief Inspector Jim Eastwood said: "My officers are working to understand what has happened to this man, and we need the public’s assistance.
Metropolitan Police file photo
Nick Potts
“I’m asking for anyone with dash cam or cycle helmet footage to contact us if they were using the Western Avenue A40 Eastbound in the proximity of Cayton Road and Welland Gardens between 15:15hrs and 16:15hrs.
"The elderly victim, who was riding a mobility scooter, was in the area at the time.
"If you saw the victim, or captured anyone acting suspiciously in the area, it is imperative that you make contact.”
Chief Superintendent Sean Wilson said: "This is an awful incident that will understandably cause considerable alarm to people locally and across London. Our thoughts are with the elderly victim.
"We are supporting our colleagues in Specialist Crime as they work to understand what has happened and identify who is responsible for this horrific crime.
“The support of the public is crucial. Police and the community must work together to identify violent offenders and remove them from our streets.
“My officers will remain on scene. They are there to help and protect you – if you have information that you want to share please approach them and tell them what you know.”
A crime scene is in place in the area and police have confirmed no one has been arrested at this stage.