Newly released surveillance video from a Chicago high school shows police officers dragging a 16-year-old girl down a flight of stairs, punching her and using a stun gun on her. The girl’s family has filed a lawsuit against the school, police and others.

>> Read more trending news

The video appears to contradict the account officers gave of the Jan. 29 incident at Marshall High School, according to an amended federal lawsuit filed Thursday by the girl’s attorney, Andrew M. Stroth.

"Thank God for that video," Stroh told ABC 7. "When this instance first happened the state's attorney charged a 16-year-old unarmed girl with two felonies for aggravated assault against a peace officer."

The charges were dropped a week later “in the interest of justice,” prosecutors said.

The day of the incident, the girl had been asked to leave school for having her cellphone out in class, the lawsuit said. At the girl's initial hearing, prosecutors said the officers had been called to escort her out of the building, but that she kicked, bit and spit on the officers, The Chicago Sun-Times reported.

Stroh argued in the lawsuit that the video is proof the officers lied about the girl being the initial aggressor.

The video shows the girl standing in a hallway as two police officers stand by. The girl is seen hugging another student, who then walks away, the Sun-Times reported. The girl moves away from a nearby stairwell, and an officer appears to grab the girl and push her down the stairs, according to the Sun-Times.

Another security camera near the bottom of the stairs captured the officer dragging the girl down the stairs by the leg. Another officer appears to be falling down the stairs while holding onto the girl from behind.

As the girl lays on the ground at the base of the stairs, one officer appears to step on her while the other officer appears to punch her. One officer then shocks the girl with a stun gun.

The girl’s father, Laurentio Howard, arrived at the school to pick his daughter up and witnessed the end of the altercation.

"I couldn't believe I seen two sworn police officers of Chicago abusing my daughter like this, and I'm standing right there watching them do this and can't do anything about it," Howard told ABC 7.

The lawsuit names the city, the two officers and the Chicago Board of Education in the U.S. District Court for the Northern District of Illinois, accusing them of violating the girl's civil rights and physically abusing her without justification, CNN reported.

Police spokesman Thomas Ahern told the Sun-Times that officials cannot comment on the new video because the incident is being investigated by the Civilian Office of Police Accountability.

Chicago Public Schools spokeswoman Emily Bolton issued the following statement Thursday:

"CPS is committed to creating a safe and supportive learning environment for all students and we are deeply disturbed and troubled by this incident which has no place in our schools. The CPS Office of the Inspector General is conducting a review of the situation upon the district's request, and we are fully cooperating in the investigation by the City's Civilian Office of Police Accountability.”