London mayor Boris Johnson faced a barrage of criticism from angry residents as he toured the devastation in riot-hit Clapham with Home Secretary Theresa May.
Mr Johnson, who flew back from his summer holiday yesterday as the violence escalated across the capital, said: "I want to say to everybody who runs a shop or owns a business here how very sorry I am for the loss and the damage you have suffered.
"I also want to say to the people who have been involved in instigating these riots and those who have been robbing and stealing that they will be caught, they will be apprehended and they will face punishments they will bitterly regret. They will.
"I know there are questions about the police response and police numbers. We are certainly going to be dealing with those."
Mrs May was led away by aides as a visibly-stunned Mr Johnson faced the television cameras and public wrath.
One woman told him: "I was in a salon when a brick came through the window and no one was here to defend me."
Another woman shouted at the mayor, urging him to resign.
Mr Johnson struggled to make himself heard as he said: "Tonight we are going to have a huge number of police on the streets."
He added: "It is time that people who are engaged in looting and violence stopped hearing economic and social justification for what happened."
The mayor, who was eventually guided away from the crowds and television cameras, followed other leaders by ending his stay abroad to join efforts to quell the violence that has blighted London.
The move came despite Mr Johnson's aides previously insisting he could deal with the burgeoning crisis remotely as if "he was sitting in his office".
Mr Johnson arrived at a cordon outside Clapham Junction station where members of the public gathered.
He was to greeted by the sight of a burnt-out fancy dress shop being hosed down by firefighters, surrounded by litter strewn on the streets and smashed windows.
Crowds of people armed with brooms waited for permission to enter the cordon, which covered St John's Hill and Lavender Hill, to start a clean-up operation - a movement started on Twitter.
The mayor walked the length of devastated streets, past window after window of shops that were smashed in the riots last night.
Mr Johnson received a mixed reaction veering from almost carnival spirit to anger and rage.
He managed to turn ill-feeling to positive at one point by taking hold of a broom and thanking crowds for turning out.