The apparently deliberate targeting of a venue filled with young people marks a repulsive new low in the acts some people will perpetrate to undermine our values, to try to break our society.
We awoke to find - yet again - that our old certainties were under attack.
The BBC phoned me to ask what school leaders would be doing today. From 15 years as a secondary headteacher, here’s what I know. It’s not that I ever had to deal with a situation on the devastating emotional scale of Manchester. But like all schools, like all organisations, the unpredictable can puncture the routines of school life. It did for us occasionally.
My guess is what school leaders know foremost is that those routines matter. Schools are safe places, and part of their safeness derives from the clearly enforced routines - the assemblies, the lesson changeovers, the familiarity of register names being called out and answered.
I learned early on in headship that when the world outside appears to have fallen apart, you make sure the world inside remains reassuringly familiar. Routines today will have carried many through, helping to keep emotions and speculation to be kept at bay.
But I also know that what school leaders will have done is to legitimise discussion about the events of last night. In English or history lessons, in tutor time and science, teachers will have allowed students to express their horror, their bewilderment. They’ll have asked students to pause, and perhaps bow their heads in solidarity with the victims. They may have opened up a website to look with students about the latest developments.
In this way - in an era of fake and sensationalist news - our teachers will have modelled a civilised, thoughtful response to events we can hardly comprehend. They will have been teaching young people how we - the adults they look to - navigate through a sometimes dark and baffling world.
Finally, across all schools and colleges, whatever their intake, today will be a day when their sense of community, of cohesion, will have been to the fore. More staff will have been on duty, mingling with students, talking to them, asking how they are. It’s a sign of how civilised many of our schools are that students are likely to have asked about the wellbeing of staff.
In assemblies, in classrooms, the lunch queues, there will be a heightened awareness of how lucky we are - to be part of a community, to be with people who care, to be alive.
Being a teacher, being a school leader - these are never easy jobs. Too much of what they do goes unnoticed. Today, quietly and without fanfare, the education profession will have done us proud.
As a contrast to last night’s act of such abhorrence, we can’t thank them enough.
Geoff Barton is the general secretary of the Association of School and College Leaders. He tweets @RealGeoffBarton.
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