After campus police used pepper spray on student protesters supporting the Occupy Wall Street movement, the head of the California university has launched an investigation into the incident.
Video footage of the incident, which occurred on Friday on the campus of University of California, Davis, was captured on mobile phones and has circulated widely on the internet.
Linda Katehi, the chancellor of UC Davis, described the video images as "chilling" and said she was forming a task force to investigate, bur rejected calls from within the university for her resignation.
"The use of the pepper spray as shown on the video is chilling to us all and raises many questions about how best to handle situations like this," Katehi said in a message posted on the university's website on Saturday.
The protest was held in support of the overall Occupy Wall Street movement protesting against economic inequality and in solidarity with protesters at the University of California, Berkeley, who were jabbed by police with batons on November 9.
Calls for resignation
Footage of the incident prompted immediate outrage among faculty and students, with the Davis Faculty Association saying in a letter on Saturday that Katehi should resign.
"The Chancellor's role is to enable open and free enquiry, not to suppress it," the faculty association said in its letter.
It called Katehi's authorisation of police force a "gross failure of leadership."
Nathan Brown, an assistant professor at the university, wrote in an open letter to the chancellor: "You are unfit to ensure the safety of students at UC Davis. In fact: you are the primary threat to the safety of students at UC Davis. As such, I call upon you to resign immediately."
At a news conference later on Saturday, Katehi said what the video showed was "sad and really very inappropriate".
The events surrounding the protest had been hard on her personally, but she had no plans to resign, she said.
"I do not think that I have violated the policies of the institution. I have worked personally very hard to make this campus a safe campus for all,'' she said.
Charles J Kelly, a former police lieutenant in Baltimore who wrote the department's use of force guidelines, said pepper spray was a "compliance tool'' that could be used on subjects who did not resist, and was preferable to simply lifting protesters.
"When you start picking up human bodies, you risk hurting them,'' Kelly said. "Bodies don't have handles on them.''
After reviewing the video, Kelly said he observed at least two cases of "active resistance'' from protesters.
"What I'm looking at is fairly standard police procedure,'' Kelly said.
Images of police evictions have served to galvanise support during the Occupy Wall Street movement, from the clash between protesters and police in Oakland last month that left an Iraq War veteran with serious injuries to more recent skirmishes in New York City, San Diego, Denver and Portland.
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In the video of the UC Davis protest, the officer, a member of the UC Davis police force, displayed a bottle before spraying its contents on the seated protesters in a sweeping motion while walking back and forth.
University spokeswoman Karen Nikos said nine people hit by pepper spray were treated at the scene. Another two were taken to hospitals and later released.
Nikos declined to release the identity of the officer in the video. Annette Spicuzza, the UC Davis police chief, told the Sacramento Bee newspaper that police used the pepper spray after they were surrounded.
Protesters were warned repeatedly beforehand that force would be used if they didn't move, she said.
"There was no way out of that circle," Spicuzza said. "They were cutting the officers off from their support. It's a very volatile situation."