A substitute teacher was arrested and fired after she violently assaulted a female high school student in Kyle, Texas, on Friday.

Police charged 32-two-year-old Tiffani Shadell Lankford with second-degree felony aggravated assault after she punched a 15-year-old Lehman High School student multiple times in the head as she sat at her desk.

Video footage shows the student raise her arm near Lankford’s face as the situation escalates. Moments later, the teacher pulls the teenager out of her chair, throws her to the floor, and stomps on her head.

A student who witnessed the altercation said prior to the assault, her classmates were laughing as Lankford passed out papers. However, she reportedly became aggravated which resulted in a verbal argument with the victim.

“The student said ‘shut up’ back. She said, ‘No, you shut up,’ and the teacher got in the student’s face and put her hand on her chest and her other hand on her arm,” the 10th grader recalled.

“The student swung because she was in her face and pressing her. The teacher put down her glasses – she swung like three times, pulled her to the ground and stomped on her head.”

The girl was taken to the hospital for medical treatment and was reportedly kept in a dark room over the weekend to recover from a brain injury.

Her lawyer said she had appointments with a neurologist and trauma doctor, and also suffered from “acute post-traumatic anxiety,” according to WFAA.

In an email Friday, Lehman High School Principal Karen Zuniga informed parents of the incident.

She wrote:

This afternoon, we fired one of our guest teachers for hitting and fighting with a student. Under no circumstance is that behavior tolerated at Lehman High School or in Hays CISD. Additionally, the former employee was arrested by the Hays County Sheriff’s Office and faces potential criminal charges. Her actions will also be reported to the Texas Education Agency. We take the safety and security of our students seriously. We took swift action when this incident occurred and will do everything necessary to protect our students.

“There is absolutely no excuse or circumstance that can justify what you see unfold on the video,” said school district spokesman Tim Savoy. “It is unconscionable what this adult did to one of our students,” he concluded.

Lankford was hired by Hays CISD in August and worked in district classrooms a total of 18 times. She had also been through training and passed background checks prior to the incident.

Samara Valdez, a student who plays on the basketball team with the victim, said she was shocked after she saw the footage.

“I saw the video, and I started crying because it’s my teammate,” she said.