General David Petraeus' rocky first days as a lecturer at the City University of New York only got rockier this week. Six CUNY student were arrested on Tuesday while protesting outside Macaulay Honors College, where Petraeus holds his classes. Now their supporters are saying that police unnecessarily roughed the students up during their arrest, and video footage seems to support that claim.

The video above shows one of the arrested demonstrators being immobilized by NYPD officers after a clash between the protesters and police had already begun. At about 30 seconds into the video, you can clearly see a police officer kneel down and punch the demonstrator's exposed kidney area. Ultimately six students, ranging in age from 18 to 25, were taken into custody and charged with mutliple crimes, "including disorderly conduct, riot, resisting arrest and obstruction of governmental administration," according to the Guardian.

In response to the video, and to support the ongoing campaign against Petraeus, a group of graduate students and professors gathered together yesterday to pen an open letter that voices their displeasure with Tuesday's arrests and Petraeus' hiring:

As graduate students and educators of CUNY, we express our outrage at the violent and unprovoked actions by the NYPD against CUNY students peacefully protesting the appointment of war criminal David Petraeus as a lecturer at the Macaulay Honors College. We deplore the use of violence and brutal tactics against CUNY students and faculty who were protesting outside the college. It is unacceptable for the university to allow the police to violently arrest students.

Originally a CUNY project, the letter, which asks for the charges against the students to be dropped and for Petraeus to be fired, has now been signed by hundreds of academics from around the country.

After being arraigned on Wednesday, the six students who were arrested are due back in court on October 17.