A promising teenage footballer was stabbed to death in front of horrified families after being chased through a west London estate.

Abdullahi Tarabi, 19, collapsed in an alleyway after being knifed in the stomach as he fled two people near his home in Northolt at about 3.30pm on Tuesday.

Witnesses said the teenager cried for help before his brother tried dragging him to the safety of a nearby house in Newnham Close.

They said paramedics battled to Mr Tarabi as his “screaming” family looked on before rushing him to hospital. He was pronounced dead just after 5.30pm.

He is thought to be the sixth teenager killed in the capital since the start of 2017. His death was the second fatal stabbing in 24 hours on London’s streets.

Schoolmates from the Alec Reed Academy in Northolt, formerly known as the West London Academy, today described the young man as a talented footballer “with a lot of potential”.

Close friend Kallum Reed posted a heartfelt tribute to the teenager he knew his “whole life” on Facebook, saying: “I remember him being just full of energy and full of life. He was always laughing and making jokes so it leaves me confused and hurt that he’s been taken from us at a very young age.

“I will definitely miss seeing him about, he was a special soul. I hope you rest in perfect peace my brother.”

A friend and local teaching assistant wrote on Facebook: “Such a popular kid, had so much memories with this guy and now his young life has been taken. RIP Little Tarabi.”

“For someone who works with young people, it hurts me the most that there’s nothing being done to stop young people from carrying knifes. Is it ever going to stop?”

Forensic officers could be seen combing the quiet suburban estate for evidence yesterday as residents struggled to comprehend the “nightmare” that had unfolded on their doorstep.

One neighbour, who did not want to be named, said he saw Mr Tarabi desperately fleeing across the road from two men of a similar age.

He said: “I was coming home from buying my son food. When I saw the boy running I stopped my car to see what was happening.

“I saw the two guys chasing the boy down the alleyway. The boy was running, but he couldn’t run any more. They stabbed him once and ran away, and he was calling ‘Help, help’.

“It was something that I didn’t want my son to see. It’s still in his mind, it’s going to disturb him for a while.

“It was a long knife. I thought it was a joke, it was like a movie. Even the way he stabbed him, it was so quick – he didn’t even touch him.

“It was a nightmare.”

Relatives gathered at Mr Tarabi’s family home in Northolt last night were too upset to comment.

One friend said had heard about the stabbing shortly after landing at Heathrow following a family holiday.

Fighting back tears as he stood at the police cordon on Newnham Close, he said: “He was a close mate of mine. He was a top guy.”

Another neighbour said: “He was laying down on the floor and the police were trying to save him for a good hour. He was completely out of life.

“His brother there, and then his family all came and his mother was screaming. They saw him. His brother had dragged him from the alley.

“It made me cry.”

Four men were arrested shortly after the attack and were being questioned at police stations today on suspicion of murder.

The stabbing comes during a bloody period of street violence in the capital. A 24-year-old was knifed to death yards from his home in Plumstead on Monday.

And 16-year-old Karim Sams, a member of an anti-gang boxing academy, was shot dead near City airport on Friday night.

Any witnesses or anyone with any information can call police in Ealing via 101, or by tweeting @MetCC

Information can also be reported anonymously to Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.