On this day, the buses instead took them less than a mile away to a recreation center to be reunited with frightened relatives, who had just learned that their school was now on a dreadful and ever-growing list.
STEM School Highlands Ranch in Colorado, a K-12 campus about seven miles from Columbine High School
, became the latest site of a school shooting on Tuesday, when two suspects opened fire in classrooms killing one student and injuring eight others. Two suspects are in custody, police said.
Photographs of the children taken after the attack show childhood invaded by tragedy.
Many of those on campus during the shooting were at an age where they might still reach for a parent's hand to cross the street.
One student told CNN affiliate KCNC that he thought it was a drill -- a lockdown was announced over the intercom system -- but then he saw a law enforcement officer with a rifle.
"We didn't really expect something like this. We didn't hear any sort of threats. There's a lot of things wandering in our minds -- 'Who could've done this? Why did it happen?'" the boy, who said his name was Adam, told KCNC.
STEM School parents are now left to comfort their children through an inexplicable, though increasingly common, event.
On Tuesday, parents held their children and kissed their foreheads as the children cried.
In a crowd intermixed with law enforcement officers and relieved families, a man placed his arm protectively around a young boy and used the other to offer a leading hand.
A woman held tightly to a child in her arms, kissing the little one's cheek.
Two children turned to one another, looking bewildered but embracing as they and their classmates were evacuated from the place they go every day to learn and to play.