An eyewitness, walking back from the display at Waltham Forest Town Hall on Sunday night, told The Independent: “I saw three young men laying on the pavement being attended by paramedics.
“They were stabbed in the back, at least two of them. All were left [face down on] the pavement.”
He added: “I saw two moving and conscious, thankfully. I saw family members rushing towards the scene screaming and shouting while I was leaving.
“The stabbing happened at the beginning of the market and it’s quite busy there at all times”.
A Metropolitan Police spokesperson said police were called at 9.20pm on Sunday to reports of three men with stab injuries.
They added: “The three men were treated by paramedics at the scene before being taken to hospital. A fourth man was also found with stab injuries and he was taken to hospital.
“The conditions of the four men have been assessed as non-life-threatening.
“All four have been arrested on suspicion of affray and they remain in police custody.”
The council event was described as a more “environmentally conscious event” telling the history of the borough, with traditional fireworks replaced by a specially created light show.
It came as fire crews were attacked and eight police officers injured in Bonfire Night disorder which saw petrol bombs, fireworks and other projectiles thrown at riot police, buildings and vehicles in Edinburgh.
Around 100 youths gathered on Hay Avenue in Niddrie, Edinburgh, just before 5pm on Sunday in a repeat of the disorder seen last year in the neighbourhood.
Police Scotland assistant chief constable Tim Mairs said that while the majority of Scotland enjoyed Bonfire Night, “Police Scotland officers were subjected to unprecedented levels of violence.
“A minority of individuals have been responsible for an unacceptable and frankly, disgusting level of disorder that left communities alarmed and police officers injured.
“The violent nature of the situation witnessed in the Niddrie area of Edinburgh is extremely concerning, not least because it is believed young people were being actively encouraged and coordinated by adults to target officers while they carried out their duties.”
Scotland’s first minister Humza Yousaf branded the incidents “disgraceful” and said those responsible should feel the full force of the law.
Drone footage from Niddrie showed a line of police officers with riot shields standing in front of vans with blue lights flashing.
A group of youths gathered on the grass in front of them and began throwing pyrotechnics.
The police made a retreat as a petrol bomb hit the ground in front of them and fireworks exploded.
Footage filmed from a nearby sports centre showed petrol bombs and fireworks forcing police to shuffle backwards before the officers ran at the assailants.
In Dundee, two police vehicles were struck by bricks in the Beauly Square area, while in Glasgow police received a report of two separate groups of youths fighting and throwing fireworks at one another in Barmulloch.
Police Scotland said there were a small number of arrests made with further arrests anticipated to follow as investigations continue.
In 2018, Police Scotland set up Operation Moonbeam to tackle Bonfire Night disorder.
Scottish Conservative justice spokesman Russell Findlay branded the youths in Edinburgh “thugs”, and council leader Cammy Day said their behaviour was “disgraceful”.
Mr Day said: “I’m appalled to see the scenes in Niddrie this evening. We’ve been clear that this sort of conduct is unacceptable.
“We’ve been working throughout the year in our communities to mitigate Bonfire Night-related disruption so it is extremely disappointing to see a minority of people behaving in this way.
“This reckless behaviour endangers lives and, like the majority, I share in their dismay and upset at this disgraceful behaviour.”
Mr Findlay said: “Such attacks on police officers are cowardly, reckless and dangerous. Police Scotland need sufficient resources to tackle these thugs.”