Two men are in hospital after being stabbed at Notting Hill Carnival, the Metropolitan Police said.
A 29-year-old man is in critical condition following an attack in Warfield Road, shortly after 9pm on Monday.
A 19-year-old man is in a serious but stable condition in a separate incident in Ladbroke Grove before 8pm.
Police said six other men, aged 18, 19, 20, 25, 28 and 40, sustained non-life-threatening injuries in separate stabbing incidents throughout Monday evening.
There were 275 arrests across the two days of the Notting Hill carnival, with 165 arrests on Monday for a range of offences.
These include possession of offensive weapons, assaults on police officers, possession of drugs and sexual offences.
Deputy Assistant Commissioner Ade Adelekan, who oversaw the policing operation, said: ‘It is regrettable that for a second year in a row, Monday night at Carnival has been marred by serious violence.
‘Nobody disputes the significance of Notting Hill Carnival on London’s cultural calendar and the overwhelming majority of those who came will have had a positive experience.
‘However, we cannot overlook the stabbings, sexual assaults and attacks on police officers that we have seen.’
The force said they will be reviewing the last two carnivals to see ‘what may need to change’.
Earlier on Monday, colourfully-costumed revellers paraded through the streets of west London, marking the climax of the Notting Hill carnival.
Thousands took part in an exuberant adult parade as part of the annual celebration of Caribbean culture and history.
Celebrities including Lily Allen, Idris Elba and Nick Grimshaw were among those partying at this year’s carnival.
It is expected more than two million people will have taken to the streets of west London by the end of the bank holiday as the carnival, Europe’s biggest street party, celebrates two landmark anniversaries.
The clean-up operation began after mountains of takeaway boxes, rubbish and drink cans were left on the sides of the roads.
Council teams have now taken on the huge task of getting the area spick and span as commuters head back to work after Bank Holiday Monday.
Hundreds of thousands of carnivalgoers enjoyed the final afternoon of the annual two-day party yesterday, which saw music take over the streets.
Mayor of London Sadiq Khan said on the first day of the celebration: ‘This is London. An amazing day!
‘The culture and creativity of Carnival shines through once again this year. Thank you to everyone working around the clock to keep Carnival a safe and spectacular celebration.’
A Windrush-themed double-decker bus was also introduced this year and was seen travelling up Ladbroke Grove.
Mr Khan added the ‘beautifully designed’ vehicle told of the Windrush generation’s ‘impact on carnival, the transport network and our city’.