Images of a man thought to have fled the scene of a "horrific" crash which killed three teenage boys have been released by police.
The boys, named locally as Harry Louis Rice, George Wilkinson and Josh Kennedy, died after a car mounted the pavement at about 20:40 GMT on Friday.
The CCTV images of the suspect were captured near the scene of the crash in Shepiston Lane, Hayes, west London.
The Met Police said it is "convinced" someone will recognise the man.
A 28-year-old man, who was in the car when it crashed and detained by members of the public before police arrived, is being held on suspicion of causing death by dangerous driving.
The images are believed to be of a second man who was a passenger in the black Audi but ran off after the crash.
Detectives have not ruled out the possibility of more passengers in the car which is believed to have been travelling at high speed before hitting a lamp-post yards from an Esso petrol station, near to junction 4 of the M4.
Det Sgt Michael Rapp from 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.
"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 victims, two aged 16 and one 17, were on their way to a 16th birthday party with a group of friends at a five-aside football venue.
George Wilkinson's grandfather, Nigel Goodhand, went to the scene on Sunday.
"I'm really cut up. It hurts. George's mother has lost the plot.
"I wasn't going to stop here, but I had to in the end", he said.
"I'm upset, but I'm pleased I've seen him. He will be sorely missed."
The Met said in a statement: "Inquiries are ongoing to establish the full circumstances of the collision and the number of occupants in the vehicle involved,"
Post-mortem examinations will be held in due course.
Other teenagers who were standing with the boys were uninjured.
One tribute left at the scene read: "George Boy, I love you so much, love Kev, Vinnie."
Another said: "I thought I would never have to write this and I don't know what to write but I will always love and miss you millions."
Elsewhere, a card read "To my bro, always together forever," while a fourth said: "To my darling baby boi my heart is broken, love mum, Vinnie."
Tony Kitchin, 44, who works as a security guard at a haulage firm nearby, said: "This road is busy 24/7. It's a speed trap.
"I'm really surprised we haven't had more horrific accidents like this.
"No parent should have to deal with that. My heartfelt sympathies go out to the family and friends of the people who lost their lives."