The details that emerge are evermore harrowing. This tragedy becomes more difficult to comprehend the more we learn and the deeper we dig.
We now believe Adam Lanza forced his way into the primary school at 9.40am on Friday morning, opening fire to gain entry.
His first victims in Sandy Hook Elementary School - he had already murdered his mother - were the Principal and a school psychologist who both raced down the corridor and towards the front door to challenge him. They were gunned down.
Then Lanza - with two handguns and an assault rifle, and dressed in black - walked down the corridor, passing one First Grade classroom. The teacher there, Kaitlin Roig, hearing the shots, had hidden her children in the bathroom. Perhaps Roig's improvised deception worked and Lanza thought the classroom was empty. At any rate, he walked on.
But then the massacre began in earnest and it was senseless violence on a previously unimaginable scale. He walked into Lauren Rousseau's class, killing her and all 14 of her young, defenceless students.
The scene does not bear thinking about.
Another teacher, Mary Anne Murphy, may also have been in this classroom. Her body was found lying on top of the corpses of young students.
It seems Ms Murphy was protecting her young charges until her last breath.
Lanza then walked into a second classroom. The teacher Victoria Soto had tried to hide her children in a large cupboard. But it seems not all of them could fit in. Six were visible and they were shot dead, along with Soto and possibly another teacher Rachel Davino.
Seven children from Ms Soto's class were later found alive by police as they secured the school building. They were still huddled in the cupboard.
Then, mercifully, Lanza turned the gun on himself.
The police who stormed the school never fired a shot.
But the most remarkable and disturbing feature of the rampage is what we do not know.
We still have no idea why Adam Lanza acted with this cowardly savagery.
Why this school?
Why such young children?
Why his own mother?
Why, why, why.