At least 22 people died in a suspected suicide bombing at a pop concert in the British city of Manchester late Monday.
Here is what we know so far about the terror attack, the deadliest in Britain since 2005.
Police said they were called at 10:33pm (2133 GMT) to reports of an explosion at Manchester Arena during a concert by pop star Ariana Grande, who is popular with teenagers and pre-teens.
According to police, the blast occurred "within the foyer area of the stadium." Manchester Arena said the blast took place "outside the venue in a public space."
The arena foyer connects the 21,000-capacity auditorium with Victoria train and tram station, a major transport hub on the northern edge of the city centre.
Witnesses described a "huge bomb-like bang" and scenes of panic as young fans rushed out and parents waiting outside frantically searched for their children.
Greater Manchester Police's chief constable Ian Hopkins said a sole attacker had set off an "improvised explosive device" and died in the process.
Authorities are treating the attack as a "terrorist incident," but no one has so far claimed it.
Police said they are now investigating whether it was a lone wolf-style attack or whether there are accomplices.
British Prime Minister Theresa May condemned it as "an appalling terrorist attack".
Hopkins said local police in the city were working with national counter-terrorism and intelligence officials on the investigation.
The bombing is the latest in a string of attacks that have hit Europe in recent years, several claimed by the Islamic State group.
Police said at least 22 people were killed and dozens injured, who are being treated in six hospitals.
The local ambulance service said on Twitter it had taken 59 casualties from the incident and treated "a number of walking wounded on scene".
Police confirmed there were children among the victims but did not give a precise breakdown of ages.
One witness, Elena Semino, told the Guardian newspaper she was with her husband waiting for her daughter by the arena's ticket office when the explosion went off.
"There was this heat on my neck and when I looked up there were bodies everywhere," she said.
Gary Walker told BBC Radio 5 Live he was hit by shrapnel in his foot and his wife sustained a stomach wound as they waited for their daughters to come out of the concert.
"We heard the last song go and then suddenly there was a massive flash and then a bang and smoke," he said.
The incident in Manchester is the second terror attack to hit England in less than two months.
On March 22, five people were killed and more than 50 injured when a man drove into pedestrians on Westminster Bridge in central London, before crashing into the fence surrounding parliament.
The attacker, 52-year-old Muslim convert Khalid Masood, was then shot dead by police at the scene after knifing a police officer to death.
Investigators described the lone-wolf attack as "Islamist related terrorism" but have not charged anyone in connection with the incident.
The deadliest bomb attack on British soil took place on July 7, 2005 when four British suicide bombers inspired by Al-Qaeda attack London's transport system, killing 52 and wounding 700.