Police are appealing for the public's help to find a man who may have been injured in an assault.
Officers were called at 13:15hrs on Tuesday, 12 March to High Street, Harlington.
Members of the public had reported seeing a man beaten, kicked and possibly struck with an object.
The suspects were described as four male youths aged in their mid-teens
Officers went to scene but the suspects had already left in a silver motor vehicle.
Enquires revealed that a member of the public had driven the victim away. Police were able to trace this driver who described the victim as an Asian male, aged between 16 to 21, who had suffered a small cut to his head which was bleeding.
He was dropped off about a mile away from the scene in Langley Crescent, Harlington.
Despite extensive enquiries police have been unable to trace the injured man.
Detective Sergeant Keith Bowen from the West Area Command Unit, said: "We are concerned that the victim may need medical attention. Our primary aim at this time is to ensure he is safe and well, and receiving the required treatment.
"We would also ask anyone who knows anything about this incident, including the victim, to contact police as soon as possible so we can identify and apprehend those responsible."
Any witnesses or anyone with any information is asked to call police on 101 or contact via twitter @MetCC. Quote CAD 3819/12MAR
To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.