Greater Manchester Mayor Andy Burnham has said a vigil will be held at 6pm on Tuesday 23 May in Albert Square, following the terror attack at Manchester Arena.
At least 22 people were killed and more than 50 injured when a suicide bomber detonated an"improvised explosive device" at an Ariana Grande concert on Monday night, as thousands of people were leaving the venue.
"Please join us for a vigil at Albert Square at 6pm tonight. We are grieving today, but we are strong," a tweet from the official Twitter account for the Mayor of Greater Manchester read.
"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," Burnham said.
"These were children, young people and their families that those responsible chose to terrorise and kill. This was an evil act.
"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."
This is the deadliest attack on British soil since the 7/7 bombings, which killed 52 people.
Greater Manchester Police have confirmed the lone male attacker died in the blast. An investigation is underway as to whether the bomber was acting alone or part of a wider network.
Prime Minister Theresa May has chaired a meeting of the government's emergency Cobra committee and is expected to travel to Manchester later today.
Friends and family of concert-goers are using social media to look for loved ones. An emergency number, 0161 856 9400, has been launched.