Why Nashville school shooting tragedy could have been even worse

As night fell in Nashville people came to pay their respects at the entrance to Covenant Christian School.

"I've just got out of work and it's all I've been able to think about all day," says Chad Baker, arriving with a bouquet of pink flowers. "I just wanted to do something."

The young and old prayed, outside this primary school which has witnessed so much pain.

CCTV released overnight gives a glimpse of the horror behind the school doors.

Audrey Hale, a biological woman who identified as a man, stalked the corridors. As a former student, they knew and had studied the layout of the building, plotting an attack on society's most innocent.

So The Covenant School in Nashville will be added to the list of school shootings that pepper the United States. Tragedies that continue in a cycle of gun violence.

And it is because of that unthinkable cycle that police here acted so fast. Fourteen minutes after the first emergency call, Audrey Hale was killed by police.

A police officer at the scene told me the authorities in the city prepare extensively for days like yesterday, with regular active shooter training.

Audrey Hale came armed with three guns and planned to attack multiple locations. What is a tragedy could have been even worse.

But that will bring little comfort to the families waking up today without their loved ones.