He told how a shop security guard disarmed a knife wielder after an 11-year-old girl and her 34-year-old mother were stabbed in London’s Leicester Square.
Abdullah, 29, said he “heard screams” and jumped on the man attacking the child, before subduing him and taking the knife from him.
“I just saw a child being stabbed and I was just trying to save him. It’s my duty just to save them,” he said.
Abdullah said he and a colleague administered first aid to the child before police arrived within four minutes of the attack on Monday morning.
Police said the girl required treatment in hospital but was not in a life-threatening condition, and her mother suffered minor injuries.
Police said a 32-year-old man was arrested at the scene and officers were not searching for anyone else in connection with the attack.
There is no evidence the incident is terror-related and police do not believe the suspect and victim knew each other.
Abdullah, who has worked at TWG Tea Shop for about eight months, said he “heard screams” and saw a person in his early to mid-30s “stabbing a child”.
“I jumped on him, grabbed his hand that was holding the knife, put him on the ground, picked him up and took the knife away from him,” he said.
“A few more people then arrived and we held him until police arrived. It probably took three or four minutes for the police to arrive and then they took him into custody.”
Police praised the bravery of those who came to the rescue.
“This is a terrible incident and our thoughts are with the victim and her family,” Detective Superintendent Christina Jesser said.
“We will continue to support them over the coming days and weeks.
“I want to thank the public, including staff from local businesses, who bravely intervened in this incident.
“You put yourselves at risk whilst showing the best of London.”
At the crime scene in central London, a popular tourist destination, bloodstained napkins and other items were found on the pavement, along with lighters and baseball caps.
The square and surrounding area is visited by an estimated 2.5 million people a week and is lined with shops, theatres, cinemas and restaurants.
A police cordon has been put up around the double doors of the TWG Tea shop, which is next to the Lego shop and in front of the M&Ms shop.
A witness posing as Darth Vader said he saw a young, white, thin man wearing a black T-shirt and jeans put the girl in a headlock and stabbed her.
The man, who gave his name as Desmond, 45, said: “It was absolutely awful, I’ve never seen anything like it. I was left badly hurt and saw a woman screaming at the top of her lungs.”
A spokesman for London Ambulance Service said they were called to reports of a stabbing in Leicester Square at 11.36am.
“We dispatched emergency services to the scene, including paramedics, paramedics and incident commanders, as well as members of our tactical response unit,” they said.
“We treated children and adults at the scene and transported them to a major trauma centre.”