"I saw everybody rush out in a panic," Tristan told CBS This Morning.
"I mean, it had to have been 400 kids, and I started to flee in my car and that's when I saw my friend Danny. He was laying in the field. He had been shot and he was surrounded by some teachers, and they didn't know what to do, so I put him in my car as fast as I could."
Tristan hauled the heavily bleeding Daniel into his car with the help of a teacher and an assistant principal and hit the accelerator.
"He was shot in the shoulder and he was scared and he didn't — no one really knew what to do — so I just put him in my car and drove as fast as I could," he said.
Ms Austin said Daniel was extremely popular and known for his habit of handing out high fives and hugs.
"Teachers love him. Students love him. I don't think (anyone) can say one bad thing about him," she told CNN.
"And that's not because I'm his mum. Everybody loves him."
She said Daniel had pulled through the first round of surgery overnight but that doctors had warned her there was a chance he may have to have his arm amputated because of the devastation wreaked by the bullet's path.
My brother means the world to me. He is one of the victims today in the school shooting. Will everyone please pray for...
Posted by Shane Story on Tuesday, 23 January 2018
Look at this Superman God thank you! He's through surgery!
Posted by Shane Story on Tuesday, 23 January 2018
Daniel's brother, Shane Story, posted an emotional Facebook tribute to his sibling on Tuesday that has garnered hundreds of likes and messages of support.
"My brother means the world to me," he wrote.
"He is one of the victims today in the school shooting. Will everyone please pray for him he's being so strong I love him to death and just for him to be hurt in this awful event is killing me inside because he's a strong funny amazing person I just don't get how anyone could do this to my little brother. I love you Daniel Austin you are going to be strong through this like everything else and I promise I'm going to take you to toys r us after this."
Another post showing a grinning Daniel post-surgery was also widely shared.
"Look at this Superman God thank you! He's through surgery!" Shane wrote in the caption.
A 15-year-old boy has been arrested and charged over the shooting.