Students and staff at the University of California, Davis, were sprayed in the face with pepper spray by campus police officers as they held a peaceful demonstration in support of the Occupy Wall Street anti-capitalist protests.
The protesters had formed a line by linking arms and were sitting on the floor refusing to move when the university's chancellor called the police to disburse them.
The police reacted by using pepper spray on the protesters, emptying canisters of the chemical spray into their faces at close-range.
A video of the police officers' actions was quickly distributed online and many people were outraged by what they saw.
In response, the university's chancellor Linda Katehi said: "The use of pepper spray as shown on the video is chilling to us all and raises many questions about how best to handle situations like this."
The two police officers involved in the incident have been suspended and an investigation into the incident is underway. However, despite calls from the Davis Faculty Association, which represents academic staff, for Ms Katehi's resignation, she has refused to do so.
The Faculty Association said: "This week, we have seen excessive force used against non-violent protesters. Student, faculty and staff protesters have been pepper-sprayed directly in the eyes and mouth, beaten and shoved by batons, dragged by the arms while handcuffed, and submitted to other forms of excessive force.
"The violence was unprovoked, disproportional and excessive. We demand that the chancellors of the University of California cease using police violence to repress non-violent political protests."
The Occupy movement started in New York on 17 September this year. Its call for social and economic equality and an end to corporate greed affected many people around the world, prompting similar demonstrations to take place.
The Occupy London Stock Exchange protest began on the 15 October and is continuing despite the camping protesters being served eviction notices by the City of London Corporation.