A third teenager has been arrested after a man was stabbed and left fighting for his life at Seven Sisters station.
Emergency services rushed to the busy north London station shortly before 9am on Tuesday to reports of a serious assault.
The British Transport Police said a man was rushed to hospital with life threatening injuries “that are consistent with being stabbed”.
A 17-year-old boy was arrested on suspicion of attempted murder on Wednesday.
A 18-year-old woman and a 15-year-old girl also remain in police custody on suspicion of grievous bodily harm with intent.
The 15-year-old has also been arrested on suspicion of common assault.
A man who witnessed the attack and helped the victim described seeing two people run into the station and emerge a few minutes later.
The witness who did not want to be named told the Standard on Tuesday: “I went downstairs, I looked around and they said a guy got stabbed. I couldn’t believe it.
“I saw him bleeding. He couldn’t breathe. He was saying ‘I got stabbed. I got stabbed.’
“Every time people come out of the station they get robbed. We need community help.”
Forensics officers wearing white overalls were seen taking photos and analysing a large crime scene outside Seven Sisters station.
A Metropolitan Police tent had been placed over an entrance to the station and a blue tarpaulin was used to hide the stairs down into an underground section of the station.
Seven Sisters had completely reopened on Wednesday following forensic investigation and police said enquiries are ongoing.
Detectives are also wanting to speak to two men seen leaving the station down the A10 towards South Tottenham station.
T/Detective Superintendent Sam Blackburn said: “There is no place for violence on the rail network and detectives are working at pace to investigate the circumstances of this incident.
“The travelling public will see increased high-visibility patrols in the area and across the network as a visible reassurance. Any witnesses who are yet to get in touch, or anyone with information around the two men, is urged to contact British Transport Police via the online portal, by calling 0800 405040, or texting 61016, reference 171 of 23 July."
