Police have released CCTV images of a man wanted in connection with a car crash that killed three teenage pedestrians on Friday night.
Investigators believe there were at least two men in a black Audi that ploughed into three friends on Shepiston Lane in Hayes.
The three victims have been named locally as Harry Rice, George Wilkinson and Josh Kennedy.
Despite the efforts of paramedics, all three boys – two aged 16 and one aged 17 – were pronounced dead at the scene.
It is understood they had been on their way to a birthday party at a nearby football club with friends when they were killed.
The Met said: “The vehicle involved is believed to have been travelling at high speed and came to a stop a short distance away from the collision.”
A 28-year-old man was detained by members of the public and has been arrested on suspicion of causing death by dangerous driving.
But one other man is thought to have been travelling in the Audi is believed to have fled the scene on foot.
The victims were with a group of friends walking towards the GOALS five-a-side football club at around 8.40pm when they were hit.
The collision occurred close to the Esso garage near junction 4 of the M4.
Witnesses standing outside the neighbouring Premier Inn told the Press Association they saw a man of Asian appearance holding a bag go sprinting down the road in the moments after the crash.
Detective Sergeant Michael Rapp of the Met’s Serious Collision Investigation Unit said: “While the images are not of good quality, I am convinced that anyone who knows this male will recognise him.
“I urge anyone who can identify him or provide details of his whereabouts to contact my team without delay.
“Three young men have lost their lives as a result of this incident; such tragic circumstances must far outweigh any taboo around assisting police.”
The first suspect is currently being held in police custody.