The Metropolitan Police have stated that a 32-year-old woman who was stabbed at the Notting Hill Carnival is in a potentially fatal situation.
Two other individuals, a 29-year-old male and a 24-year-old man, were stabbed at the west London festival, according to the force.
Approximately seven thousand police officers are on duty for this year's event, which is anticipated to draw one million spectators on Sunday and Monday.
The Met sent an update on Sunday night stating that "15 officers have been assaulted" and that 90 arrests had been made for various offences.
The alleged crimes included assault on an emergency worker, assault, possession with intent to supply, sexual offences and robbery, the police said.
"Hundreds of thousands of people came to Notting Hill Carnival to enjoy a fantastic celebration," the Met said.
"Our officers have been on duty working to keep them safe as part of a very carefully planned policing operation.
"Regrettably, a minority came to commit crime and engage in violence."
The force said a section 60 order, which gives officers additional powers to search suspects, would be in place until 02:00 BST.
Ahead of this year's carnival, the Met described it as a fixture in London’s cultural calendar that was also a "challenging event to police with very dense crowds and a regrettable history of a minority of people using it as an opportunity to commit crime, including violence".
Commander Charmain Brenyah, the Met’s spokesperson for this year’s event, said as she had grown up not far from where carnival takes place, she had "happy memories of the music, costumes, floats and fantastic atmosphere".
“Sadly, however, we know that for a minority of people, carnival is an opportunity to commit crime or to seek out violent confrontation," she said.
“As a police officer on duty in previous years I’ve seen both the carnival I experienced in my youth, but also the other side of the same event when, later in the day, the atmosphere changes in some parts, with floats and costumes giving way to serious violence."
She continued by saying that over 125 police officers had been attacked, one person had been killed, and fourteen more had been stabbed.
During those two years, the funfair resulted in about 500 arrests.
"These incidents can’t be downplayed or dismissed," she stated.
Because of this, "anyone attending a funfair will notice a very noticeable police presence. Our goal is to keep you safe, so please say hello to us, but we're also there to take decisive action against those who intend to cause violence."