The incident is one of several criminal incidents at the west London festival, which is expected to attract around one million people.
Two men, a 29-year-old and a 24-year-old, were also stabbed at the event during last night’s rally, but police said the woman’s condition was critical.
As of Sunday night, authorities had made 90 arrests for various crimes, including assault on an emergency worker, possession with intent to supply drugs, sex offenses and robbery.
Police also reported that 15 officers were assaulted during the carnival, while they were part of the seven thousand patrol officers in charge of ensuring public safety.
Despite the festive atmosphere enjoyed by hundreds of thousands of people, police said that some attendees used the carnival to commit crimes.
To address these problems, authorities significantly increased their police presence, to maintain security while being prepared to take decisive action against those intent on committing violent acts.
jrr/arm/mem/am