Mayor of London Sadiq Khan has branded a suicide bomb attack on Manchester as "cowardly" and said that the UK capital stands united with the city on Tuesday (23 May) morning.
Khan's statement comes just hours after the assault at an Ariana Grande concert at the 21,000-seat Manchester Arena left at least 22 people dead and dozens injured.
"London stands united with the great city of Manchester today after this barbaric and sickening attack," he said.
"This was a cowardly act of terrorism that targeted a concert attended by thousands of children and young people.
Khan added: "My heart goes out to the victims, their families and everybody affected. Once again we have seen the heroism of our brave emergency services. They have our full support and are in all our thoughts today.
"I am in constant contact with the Metropolitan Police, who are reviewing security arrangements in London. Londoners will see more police on our streets today.
"Manchester and the rest of Britain will never be cowed by terrorism. Those who want to destroy our way of life and divide us will never succeed."
Labour's newly elected Greater Manchester Mayor Andy Burnham also struck a defiant tone as he told reporters that the spirit of the city would prevail in the wake of the incident.
"It's hard to believe what has happened here in the last few hours and to put into words the shock, anger and hurt that we feel today. These were children, young people and their families that those responsible chose to terrorise and kill. This was an evil act," Burnham said.
"Our first thoughts are with the families of those killed and injured and we will do whatever we can to support them. We are grieving today but we are strong.
"Today it will be business as usual as far as possible in our great city. I want to thank the hundreds of police, fire and ambulance staff who worked through the night in the most difficult of circumstance imaginable.
"Lastly I want to thank the people of Manchester. Even in the minutes after the attack they opened their doors to strangers and drove them away from danger. They gave the best possible immediate response to those who seek to divide us. It will be that spirit of Manchester that will prevail and hold us together."
Prime Minister Theresa May is expected to chair an emergency meeting of the Cabinet Office Briefing Room (COBRA) on Tuesday morning. "All our thoughts are with the victims and the families of those who have been affected," she said.
All major UK political parties have suspended their general election campaigns ahead of the 8 June vote.