By chief foreign correspondent Philip Williams
There was great excitement as 20,000 fans packed into the Manchester Arena.
Ariana Grande had just finished her last song and an audience made up mainly of young girls and teenagers was starting to file out when the loud explosion changed a happy night out into a nightmare.
At first, reports suggested it was nothing serious. But, in or near the foyer, some were already dead, others maimed.
The panic quickly spread as everyone tried to get out of the arena as soon as possible. And as they ran you could hear the terrified screams.
If this was aimed at creating terror at that moment it was horribly effective.
Manchester Police released a statement about two hours after the blast saying they assumed it was a terrorist attack until proven otherwise.
It certainly looked like one. And it was an easy target, with many thousands of vulnerable young people inside and beginning to leave.
It reminded me of the slaughter at the Bataclan theatre in Paris in late 2015.
Terrorists there knew no-one would be expecting the attack on a theatre full of people enjoying a rock concert.
Since then, we have seen trucks, cars, knives and guns used against innocent civilians in many attacks throughout Europe. It’s no longer a shock when we get the news of the next atrocity.