Police have confirmed they are treating the explosion incident at Manchester Arena on Monday night following a concert by American pop singer Ariana Grande as a terrorist attack.

It is the deadliest such incident on British soil since 2005. It is believed many of the victims were teenagers.

This is what we know so far:

Police say 22 people were killed and at least 59 others were wounded

Police are calling it a “terrorist incident”

The blast occurred at 10:35pm BST

Witnesses reported two loud bangs, although the matter is still under investigation

Investigators said the explosion or explosions took place “within the foyer area of the stadium” and the venue said it was “outside the venue in a public space”.

Britain is on its second-highest alert level of “severe” meaning an attack is considered highly likely.

Nobody has claimed credit for the attack

Police say they believe the attack was carried out by a lone suicide bomber who died on the scene.

Speaking to the BBC, an eyewitness gave this account of what happened:

The apparent bombing in Manchester at the Ariana Grande concert is the second terror attack to hit England in two months. In March, five people were killed and more than 50 injured when a man drove into pedestrians on Westminster Bridge in central London. His vehicle then crashed into the gates of parliament. The attacker was shot dead by police. Nobody has been charged in connection with that incident.

London Mayor Sadiq Khan says security measures are being stepped up in the capital following events overnight in Manchester.

“I am in constant contact with the Metropolitan police, who are reviewing security arrangements in London. Londoners will see more police on our streets,” he said.