Desperate passers-by administered first aid on the 20-year-old victim following the attack in the multi-storey car park of a busy shopping centre in east London.
He was rushed to hospital where he was pronounced dead an hour later at 5.30pm last night.
The victim is the 14th person to be stabbed to death on the streets of the capital in the past four weeks.
His murder took place at the same time as Met commissioner Cressida Dick spoke to community leaders in central London about the force’s efforts to tackle London’s knife crime epidemic. A – London Live
Witnesses said the young man was ambushed and chased by a gang of youths after leaving the Brewery Shopping Centre’s Vue cinema in Romford following a matineé screening.
Jodie Freeman, 22, tried to give the victim CPR after coming across him doubled up next to a car as his girlfriend looked on in shock.
She said: “The attackers had run away, and I think his girlfriend thought he was okay. But then he fell down against the car and collapsed.
“He had been stabbed on his left side, either in the heart or close to it.
“I lay him on his back then started to put pressure on the wound. There was another man who helped me perform CPR.
“He was trying to speak but he didn’t manage to say anything. He was struggling to breathe.”
When paramedics arrived Miss Freeman, a betting shop manager from Dagenham, continued applying pressure to his chest as medics cut away the victim’s clothes.
She said: “I’m emotionally in shock, I feel guilty about it because I couldn’t do more.
“I have first aid training but this day will stay with me forever.
“After everything had happened I gave his girlfriend a cuddle and said ‘I’m sorry I couldn’t do anything more.’
“Washing his blood off my hands has got to be the worst moment of my life. I’m so sorry I couldn’t save him.
“These young people need to put the knives down. It doesn’t just affect one life it affects the people that see it happen, their families, their friends and it scares people.
“It needs to stop and more people need to be aware of what to do in that situation.”
Miss Freeman had gone into the shopping centre to buy a gift for her fiancée Sophie Watson, 21, who said: “I’m so proud of her for doing the right thing and giving him a chance.
“She’s one in a million this girl. I’m truly lucky and thankful I have her in my life.”
The first floor of the car park was sealed off behind police tape last night as detectives from the Met’s homicide and major crimes unit launched a murder investigation.
Detective Inspector Jason Prendergast, said: “This incident happened at a busy time of day, in a busy area of Romford, so we believe there are a large number of potential witnesses we are keen to speak to.
“The victim was found in the car park at end of the shopping centre next to the cinema and restaurants, and we are keen to hear from anyone who was in the area at the time of the incident.”
Any witnesses, or anyone with any information should contact police via 101, or by tweeting @MetCC.
To give information anonymously call Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.
Four men were today being questioned on suspicion of murder today at separate east London police stations.