Police are appealing for witnesses and information after two men were assaulted in Hayes.
The attack happened between 10pm and 10.30pm on March 6 as the two men walked along Atlee Road, near the junction with Ayles Road.
A group of males got out of a silver car which had driven up Ayles Road and attacked the two men - they then got in the car and drove off.
One of the victims, 45, was taken to a central London hospital where he remains in a critical condition.
The other victim, 28, was not seriously injured.
Detective Constable Mark Henry of Hillingdon Police, who is leading the investigation, said: "At this early stage it appears to be an unprovoked attack which has left a man critically injured in hospital.
"I am appealing to anyone who was in the area at the time of the incident and, in particular, who saw a silver car being driving erratically in the Ayles Road and Morrison Road area, to contact police."
Anyone with information is asked to contact DC Henry on 020 8246 1455 or call 101.
You can also tweet @MetCC.
Alternatively, contact Crimestoppers anonymously via 0800 555 111.
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