When tragedy strikes at any school, parents can't help but wonder if their kids are really safe.
Events like what transpired Friday morning at Sandy Hook Elementary School in Newtown, Connecticut, which have become far too common, have forced some Green Country schools to redesign their buildings for security.
Hundreds of small kids are walking through the halls at Owasso's Stone Canyon Elementary School.
They're all so young, so innocent, with no worries and no idea of the terrible tragedy unfolding halfway across the country.
"Every day, I'm responsible for 750 kids, and to know what those families are going through at this time is tough," said Principal George Holderman.
The Owasso school district has taken steps to try to prevent something similar from happening there. Newer schools in the district are taking measures to monitor those who come inside.
"The only way into our school building is to come in through the front office," Holderman said.
Holderman said all of Owasso's schools have been remodeled to follow this standard.
The students also practice lock down drills.
"They know that the door is to be locked and no one is to leave classrooms until myself or one of the Owasso police officers open the door for them," Holderman said.
In the Connecticut shooting, the suspect is believed to be a teacher's son. That means he could have been a regular visitor at the school and administrators may not have viewed him as a threat.
Lynn Wiltshire frequently volunteers at Stone Canyon, where her son is in the third grade.
"I feel safe here, although I know tragedy can happen at any time. You just hug your kids every day," Wiltshire said.
She said it's reassuring to know schools are always thinking of ways to better protect her kids.
"You have to check in when you come in. You wear a badge when you volunteer, so I feel like it's pretty secure," Wiltshire said.
"We do the best we can every day to keep their children safe and, at the end of the day, when I know that every child has made it back home, it's a good day," Holderman said.
A spokesperson for Union Public Schools said the district has also remodeled all of their buildings to have secured front entrances.
That means all visitors must go in through the front office.