A 17-year-old boy is in critical condition after being attacked and stabbed by two suspects wearing balaclavas.
The boy was wounded near the Easy Hotel, in Brickfield Lane, Harlington, at around 11.20pm last night (Thursday).
There was still a heavy police presence on the road this afternoon (Friday), as officers combed the scene looking for evidence.
It is believed that the victim, who was with a group of friends, was approached by two men who pushed him up against a fence before stabbing him.
The suspects were both wearing balaclavas, and one was wearing a black North Face body warmer.
The victim told police that they were both black.
Following the attack, they ran towards High Street.
A London Ambulance Service spokesman said: "We were called at 11.30pm to reports of a stabbing.
"We sent two ambulance crews, a single responder in a car, and a duty officer.
"We treated one male patient at the scene, and he was taken to hospital."
Trident, the Met Police unit which deals with gang crime and violence, is leading the investigation.
Detective Inspector Nick Murvin said: "I am appealing to anyone who may have witnessed the attack or saw the suspects running towards Harlington High Street, to contact the police.
"I would like to offer reassurance to anyone who may be worried about contacting police that they will be treated with the utmost sensitivity."
If you can assist officers with their enquiries, call the incident room 020 8785 8580, or call Crimestoppers anonymously on 0800 555 111.
