One Gwinnett middle school student is in custody, while another is being called a hero after a teacher is stabbed inside her own classroom at Trickum Middle School in Lilburn.

As classes were changing, eighth-grader Mason Watler watched as a fellow classmate pulled an 8-inch butcher knife from his bookbag and stabbed his favorite teacher in the chest.

“I saw he called over the teacher. I don’t know what he wanted; but when he did, he pulled out the knife and stabbed the teacher right under her breast,” Watler tells WSB’s Sandra Parrish.

Watler immediately went to the teacher’s aide and held his hoodie on her wound until help could arrive.

He then saw the 13-year-old suspect hold the knife to another student before being apprehended by the school’s resource officer.

“We’re very pleased that the officer was able to take the weapon away from the student without any other injuries to the officer or other students or anybody else at the school,” says Gwinnett County Schools spokesperson Sloan Roach.

She says the student faces charges of aggravated assault and bringing a gun onto school property. He will face school disciplinary action as well.

Roach says the teacher was alert and talking when she taken to the hospital.

Counselors will be at the school Tuesday for both students and teachers. The school’s principal sent out a second email to parents Monday night.

“As part of our response, we are making personal calls to the families of students who were in the classroom during this incident. That said, we are taking steps tomorrow to ensure we can support our students and staff and to help them have as normal a school day as possible. We will have an additional police presence at school tomorrow to provide our students and staff with an additional sense of security and to calm any anxiety.”

Watler says he still cannot believe what he witnessed. His mother Nikki McCart says she is proud of her son’s quick action to help his teacher.

“There were several teachers that called and thanked me and his dad, as well, for the job that we’ve done (and) for his heroism and that he just acted fast,” she says.