There has been an explosion at the Ariana Grande concert in Manchester in the last hour. There is not a lot of verified information yet, but there apparently have been fatalities.

Police say there are "confirmed fatalities" after an incident at an Ariana Grande concert. https://t.co/6WmWq25Q5T — Twitter Moments (@TwitterMoments) May 22, 2017

According to The Guardian, the explosion happened as people were leaving the concert:

Majid Khan, 22, said: “I and my sister, along with a lot of others, were seeing Ariana Grande perform at Manchester Arena, and we were all exiting the venue when around 10.40-10.45 pm-ish a huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena..”

“It was one bang and essentially everyone from the other side of the arena where the bang was heard from suddenly came running towards us as they were trying to exit Trinity Way and that was blocked so everyone was just running to any exit they could find as quickly as they could.”

One man reports being thrown 30 feet by the explosion:

Manchester Arena Blast: "Explosion through me 30 feet" says eyewitness- BBC News pic.twitter.com/vGYDYnaDMt — Liberty Belle (@invereden) May 22, 2017

Dashcam video appears to show the explosion:

https://twitter.com/TEN_GOP/status/866800130044899329

Twitter has a running Trends item for further information. An awful lot of the tweets are from people looking for missing friends.