Law enforcement officials in the United Kingdom suspect the bombing at Manchester Arena on Monday night following an Ariana Grande concert was the work of a suicide bomber, according to various reports.
The Greater Manchester Police Department reported via Twitter that the agency is treating the incident as a terror attack until proven otherwise.
In 1996, less than a mile from the Manchester Arena, the site of the explosion, - the IRA detonated a powerful truck-bomb, their largest ever on the British mainland, injuring hundreds and ripping apart the city center, causing millions of dollars in damage.
The Press Association quoted a Conservative source as saying that the prime minister's general election campaign is being suspended. "We got outside and children were crying their eyes out, people talking about it being a bomb, gunshots, there were many parents running towards the arena but no one knew exactly what it was".
Manchester residents opened up their homes to people left stranded by the incident, sending messages with the hashtag #RoomforManchester.
Toronto Mayor John Tory said the city stands in solidarity with the people of Manchester while Ontario Premier Kathleen Wynne also said in a tweet that she is "horrified" by the loss of life in the British city.
Oliver Jones, 17, said, "The bang echoed around the foyer of the arena and people started to run".
The government is urging USA citizens in Manchester to heed directions from local authorities and be vigilant about their security. Grande, who was just finishing her performance when the explosions happened around 10:35 p.m. local time, was not among the injured.
"We were making our way out and when we were right by the door there was a massive explosion and everybody was screaming", concert-goer Catherine Macfarlane told Reuters. "However, the public may experience increased security in and around public places and events as officials take additional precautions".
Eyewitnesses told local television that the Grande concert was just wrapping up when at least one thunderous explosion could be heard. "Our thoughts and prayers go out to the victims", police said early Tuesday on Twitter.
"All our thoughts are with the victims and the families of those who have been affected", May said in a statement. The government is expected to call an emergency Cabinet meeting.
A record label representative said that Grande is "OK" but did not provide further details.
"One lady told me she heard a loud explosion, they were asked to leave the arena quite quickly, they saw a number of people treated by ambulances".