A Virginia special education teacher is facing charges after she was allegedly seen assaulting a special needs student.

Amy Bonzano, 50, was arrested Friday and faces two counts of simple assault of a special needs student.

The incident at Marshall High School occurred on Sept. 28, when another school employee reported witnessing the assault, Fairfax County police said.

That employee immediately reported the assault to the school's administration, which led to an internal investigation.

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A Virginia special education teacher is facing charges after she was seen assaulting a special needs student. (Fairfax County Police Department)

During the investigation, school officials discovered another teacher had also witnessed Bonzano physically assault the student about six months earlier. That teacher, however, did not report the incident at the time.

Fairfax County police then took over the investigation, and Bonzano was arrested on Friday.

Marshall High School principal Jeffrey Litz wrote a letter to students' families after the arrest in which he explained that Bonzano had been placed on administrative leave after the Sept. 28 assault was reported.

"I am deeply saddened tonight to inform you that Fairfax County police have announced the arrest of a special education teacher at Marshall High School who has been charged with assaulting a student," Litz wrote. "When the alleged incident occurred on September 28th, we contacted the family and the proper authorities, and placed the staff member on administrative leave." 

The incident at Marshall High School occurred on Sept. 28, when another school employee reported witnessing the assault, Fairfax County police said. (Fairfax County Public Schools)

Litz also said the teacher who failed to report the earlier incident was placed on administrative leave as well.

"As the police reference, the investigation resulted in a staff member sharing that they had witnessed a similar incident six months earlier but did not report it," he wrote. "I want you to know that the person who did not report the previous incident was immediately placed on leave."

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Amy Bonzano, 50, was arrested Friday and faces two counts of simple assault of a special needs student. (Eric BARADAT / AFP/ Getty Images)

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"As principal, my primary responsibility is the safety and security of everyone who enters the doors of Marshall High School," Litz continued. "This is something I take very seriously. As educators, we are entrusted with the wellbeing of the children in our care every day. It deeply affects us when someone appears to have broken that trust."

Marshall High School did not immediately respond to a request for comment from FOX News Digital.