A man is being treated in hospital after being stabbed on a packed commuter train in east London on Tuesday evening, police have said.

One man was arrested after what British Transport police called a “serious stabbing”, which happened on a London Overground train at Hackney Central station shortly after 6pm.

A witness said he saw a man wielding a knife as he entered the station shortly after the incident. “I saw loads of people running towards me … and a woman said: ‘There is a guy with a knife’ and that he had stabbed someone on the train,” Nick Renaud-Komiya said.

He told the Guardian: “I caught a glimpse of the guy with the knife coming towards the walkway. He had the knife in his hand. The police came within a minute-and-a-half. They grabbed him and he was shouting [but] I couldn’t make anything out.” Renaud-Komiya, a 28-year-old journalist, estimated the arrested man was in his mid-40s.

Another witness, 26-year-old Hazel Orton, said she saw the victim with blood on his t-shirt shortly after the stabbing. She said he was “breathing heavily and struggling… People were trying to administer first aid and put pressure on his chest.” She described the man as being roughly 30 years old.

British Transport police (BTP) said: “Officers are appealing for information after a man was stabbed at Hackney Central Overground station earlier this evening.

“Just after 6pm, BTP officers, along with colleagues from the Metropolitan police service, were called to a report of a man having being stabbed at Hackney Central Overground Station.

“The London ambulance service has taken the victim to hospital, where he is being treated for his injuries. A man has been arrested.

“Police are asking that anyone who was at Hackney Central Overground station and saw anything suspicious to please get in touch.”