Sadiq Khan has welcomed the return of the Notting Hill Carnival three years since it was last held in streets of west London.
Revellers massed on Sunday for the opening of the festival which has become one of the biggest in the world.
London’s mayor said in a statement to mark the occassion: “I’m delighted that Notting Hill Carnival will be returning to the streets of west London this weekend.
“This community-led celebration of Caribbean history and culture has become one of the world’s biggest street festivals and part of the very fabric of this city.
“I urge everyone planning to attend Carnival to arrive early to make the most of this wonderful celebration of our capital’s diversity.”
An investigation has been launched after a police horse on duty at the carnival collapsed and died around 9pm, Scotland Yard said.
The animal was given emergency care but a force spokesman said it is too early to determine the cause of death.
As of 7.30pm on Sunday, police made 38 arrests for offences including assault, public order, sexual assault, drugs, possession of an offensive weapon, drink driving and theft.
Separately, two people suffered minor injuries when a bus shelter collapsed.
Online footage showed several revellers standing and dancing on its roof.
A large crowd is heard gasping and exclaiming in shock as the group fell through the top of the shelter.
Farah Mokaddem, 32, travelled from Geneva to attend the Notting Hill Carnival.
She said: "I always wanted to go here. The atmosphere is very animated: everyone is on their balconies and on the terrace. And people of all ages are watching as people go past."
Carina Charles said people felt "ecstatic" about the return of the carnival after the pandemic.
The 40-year-old nurse, from Basildon, said: "I like the togetherness of the people and the mixture of the culture.
"My Caribbean music, the Soca music, is what I love the most."
She added: "Everybody is jovial - they are excited after coming out of lockdown after three years.
"Everyone is ecstatic about the return of carnival after lockdown."
On Sunday morning, large crowds gathered for J’Ouvert celebrations, where revellers sprayed coloured paints and powders on each other to kick off the festivities.
On Saturday evening more than 1,000 people gathered to watch the Panorama steelband competition.
Revellers flocked to Emslie Horniman’s Pleasance Park, in west London, to watch a curtain-raiser featuring five steel bands – Mangrove, Croydon Steel Orchestra, Ebony, Metronomes, and Pan Nation.
Defending champions Mangrove have won for three years in a row, and member Joelle Gardiner, 34, said: “It is hard to put into words how good it would feel to win tonight.”
“I have been coming to carnival ever since I was six or seven, watching people play until I was at the age where I could get involved as well.”