The school district provided counselors and stepped up security for Linbdergh's students and staff.
"I know that in our counseling department we had many extra hands on deck," St. Joseph School District's Jake Long said.
No threats were made with the gun as the boy showed it off to his friends.
It was still shocking however, for students and parents to hear that a loaded gun made it in the building.
"My two grand kids are checked every morning to make sure they have the right stuff to go to school," Grandparent Ron Newberry said.
The district wouldn't say if the child returned to school on Wednesday, but did say they are following district guidelines.
"We're going to do what is in accordance to our discipline code," Long said.
Principal Julie Gaddie and other administrators at Lindbergh worked into the evening fielding more than 150 calls from concerned parents.
"It's a reminder that we are partners with parents and our community, and ensuring that our schools are safe places to attend," Gaddie said.
The boy's father, 28-year-old James Mueller, is charged in the case with unlawful possession of two firearms and providing access to two children under the age of 8.
He's been in trouble before for drugs, sexual and domestic assault and child support. Police questioned both parents in the case.
Meanwhile, school leaders are brainstorming ways to prevent anything like this in the future.
"In fact we've already started the process in looking at any kind of curriculum that may be out there that we can use to educate our kids on gun safety," Long said.
The district will also sit down and have meetings to evaluate their response.