Right after Christmas break, the Broward County Public Schools held their system-wide intruder and active-shooter training.

As it does each each year, the Broward County Sheriff’s Office met with the teachers and staff at each facility—including Marjory Stoneman Douglas High School—and went over the procedures in the event an active shooter invaded the building.

The officers reminded them nobody should imagine that the horrors of Columbine and Sandy Hook and so many other schools could not happen there in Broward. Marjory Stoneman Douglas High School was not exempt simply because the surrounding town of Parkland had been declared the safest city in Florida in 2017.

The officers also emphasized that in the event of a lockdown, everybody should remain in place.

“They said, ‘Tell your kids if they hear a fire alarm or if somebody knocks on the door and says ‘Let us in,’ don’t open the door for anybody,’” a Broward teacher who attended the training told The Daily Beast.

The deputies told the teachers at each school in January essentially what Broward County Sheriff Scott Israel would say in the aftermath of what was to come the very next month.

“If you see something, say something.”

The teachers then passed on their training to the students. The schools held lockdown drills, as they had regularly for years.

One student who had been in at least a half dozen such drills but missed this year’s at Marjory Stoneman Douglas High School was Nikolas Cruz. He was expelled last year, by some accounts for threatening classmates.

By several accounts, he was known to be fascinated with firearms and had shown fellow students cellphone pictures of guns. The school reportedly forbade him from venturing onto campus with a backpack, almost certainly as a precaution against him using it to carry a weapon.

But while he was subjected to a backpack ban, Cruz had turned 18 and there was nothing in Florida law to keep him from buying an AR-15. He also obtained a considerable number of magazines.

Cruz posted on Instagram a photo of the AR-15 set out on his bed along with a small arsenal of other weapons. Somebody certainly saw something. But nobody seems to have said anything.

As Cruz was a guy who seems to have had considerable problems and little success with girls, his decision to revisit the school on Valentine’s Day was not likely a coincidence.

Cruz quite literally knew the drill when it came to active shooters and understood that the lockdown procedure would go into effect the moment gunshots were heard. He certainly did not want to find himself wandering suddenly deserted hallways, trying to force his way through locked doors.

So Cruz seems to have hatched a two-part scheme to thwart the well-rehearsed lockdown plan.

He began by waiting until just five minutes before the 2:35 p.m. dismissal time.

He then pulled a fire alarm.

The timing likely made it more difficult for the school to order and maintain a complete lockdown. He was able to kill 12 inside the school, along with another two just outside and one on the street. Three more died in the hospital.

The toll could have been higher had the students in at least two classrooms not stayed put despite the fire alarm and despite a banging on the door that was almost certainly the gunman.

One stalwart soul was a 17-year-old junior named Matt Walker. He managed to make a cellphone video as the gunman fired through a glass panel in the locked classroom door, the shots coming jarringly loud and as fast as his finger could pull the trigger of his AR-15. Walker recorded screams and shouts of “Oh my God!… Oh my God!” as well as more and more gunshots as his classmates crouched in total terror.

To watch that video is to know that something must be done, that we have to do all we can to stop it from happening again.

In the aftermath of this latest school shooting, the worst since 20 youngsters and six adults were murdered with an AR-15 at Sandy Hook in 2012, a shaken Sheriff Israel stood before the press. His own triplets had graduated from what was now a mass murder scene.

Israel told reporters that along with the assault rifle, Cruz had “endless magazines, multiple magazines.” Israel’s tone suggested that this translated in his mind to murdered kids.

Israel also spoke of Cruz’s online postings.

“Very, very disturbing,” Israel told the press.

Israel repeated what his deputies had urged at every school in January, words that might have saved 17 lives if somebody had seen those disturbing postings and called the police.

“If you see something, say something,” he said, adding, “If anybody has any indicator that someone’s going through a behavioral change or on their social media that there are disturbing photos, perhaps bombs or firearms, or just videos or pictures that are just not right, please make sure law enforcement knows about it.”

Outside the school where the latest active shooter drill had been held just last month, parents stood waiting to learn if their children were among the dozen dead whose bodies would remain inside until the investigators and photographers and forensic people were done.

The foreheads of a number of parents bore crosses made with the soot of palm fronds, for this year Valentine’s Day was also Ash Wednesday, when the faithful are supposed to ponder their mortality.

For all the moms and dads, this was no longer a day of flowers and chocolates. And for even the most devout of those who had received the symbolic ashes earlier in the day, no ritual could have prepared them for this present moment. They stood facing the prospect of their child’s mortality as the result of high-velocity bullets.

Just as the classroom video told you something must be done, these faces of the moms and dads told you that whatever our leaders do, it must be more than simply offer prayers and then continue on until the next time and the next and the next.