Ed Chelby, a U.S. Army veteran who has a background in security, told KWTX that he couldn't sleep after news emerged that an 18-year-old gunman killed 19 children and two teachers on Tuesday at Robb Elementary School.

Chelby said he contacted the school's superintendent to ask for permission to stand guard at the main entrance of Saegert Elementary School in Killeen, which is located about 180 miles northwest of Uvalde.

"I said I would just be out there unarmed to let people know that I'm watching. Let the parents have a little bit of relief," Chelby said in an interview with the local news station.

"I can't let this go," he added.

"This is just a testament to the sleeplessness caused by the grief I experienced."

The U.S. Army veteran was already in the process of becoming a volunteer at his daughter's school and was undergoing a background check when the superintendent approved his application to stand guard outside.

Chelby said with 11 years of experience in the U.S. Army, he isn't afraid to be in front of the school without a gun.

Parents of other children at Saegert Elementary School have approached Chelby to express their gratitude for what he's doing.

"I've had a lot of emotional people come up to me," he said,

"They didn't want to send their kids to school. They struggled with sending their kids to school. And I told them, I was like, 'I got them.'"