Police use of pepper spray on a dozen protesters at University of California, Davis, on Friday sparked calls for the resignation of the university’s chancellor and the start of an investigation into the incident.

Videos of the Davis incident uploaded to YouTube show police officers dousing the protesters — mostly students, according to local reports — with orange pepper spray, after repeatedly asking them to disperse from the main quad on campus. The protesters were seated with their arms linked on a sidewalk.

A video posted by the user terrydatiger showed the incident from the side.





A second video, posted by a user named asucd, showed the perspective from behind the chain of protesters.

Eyewitnesses uploaded their recordings late Friday. In a statement on Saturday that acknowledged the role of the eyewitnesses in raising awareness about the police’s behavior, the university’s chancellor, Linda P.B. Katehi, said she was saddened by “the events.”

“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,” Ms. Katehi wrote. Her statement said that she was forming a task force and asking university officials to review existing policies about encampments like the one that was erected on the campus this week.

“While the university is trying to ensure the safety and health of all members of our community, we must ensure our strategies to gain compliance are fair and reasonable and do not lead to mistreatment,” Ms. Katehi wrote.

Asked about the demands by some faculty members for her resignation, Ms. Katehi said at a news conference on Saturday afternoon that she did not deem it appropriate to resign “at this point.”

This week also saw arrests of protesters in more than a dozen states and the eviction of protesters from the birthplace of the two-month-old Occupy Wall Street movement in New York City. Pepper spray was used, too, in Seattle on Tuesday night.

More than a dozen videos of the Davis incident have been uploaded to YouTube. The most-watched video has been viewed more than 200,000 times, according to the Web site. The videos have generated outcry online and were rebroadcast on television on Saturday. A reference to the pepper spray use was the No. 1 trending topic on Google in the United States on Saturday afternoon.

In one of the videos, the officer steps over a line of seated protesters, holds the pepper spray bottle in the air, then sprays it in the protesters’ faces in a coordinated fashion as eyewitnesses gasp and shout, “Shame on you.” Most of the protesters remain seated; police officers then forcibly remove and arrest them.

In a video taken from another direction, two officers can be seen dousing protesters with pepper spray at the same time. Though not visible in the videos, the operator of the Facebook page for the Occupy U.C. Davis organization claimed that one police officer “shoved a pepper spray gun down a student’s throat and pulled the trigger.” On Saturday afternoon, the Facebook page announced that protesters would be working with attorneys to pursue legal action.

In the video, after the arrests, protesters and bystanders are seen asking the police to leave. “You can go,” they chant. The police then appear to walk away from the quad, to applause from protesters.

A spokesperson for the U.C. Davis police did not respond to a request for comment Saturday. Annette Spicuzza, the U.C. Davis police chief, told The Sacramento Bee that the officers used pepper spray on Friday because the police were surrounded by students. “There was no way out of that circle,” she told the newspaper. “They were cutting the officers off from their support. It’s a very volatile situation.”

The videos, however, show officers freely moving about and show students behaving peacefully. The university reported no instances of violence by any protesters.

The listed phone number for Ms. Spicuzza indicated on Saturday that her voice mailbox was full.

The pepper spray incident took place at the end of a week of peaceful demonstrations on the U.C. Davis campus. According to Ms. Katehi’s statement, a group of protesters set up about 25 tents on the campus quad on Thursday in violation of university policy. Such encampments have been part of the strategy of Occupy-aligned protesters in cities and towns across the country.

The campers were told on Thursday and Friday that they had to remove the tents. Ms. Spicuzza said she decided “not to allow encampments on the quad during the weekend, when the general campus facilities are locked and the university staff is not widely available to provide support.”

Some of the protesters removed their tents, but others did not. When the police took the tents down, some of the remaining protesters locked arms and refused to move, leading to the pepper spray use.

Two protesters were hospitalized afterward, according to local reports. Ten were arrested.

Kristin Koster, who helped one of the protesters, Dominic Gutierrez, told The Davis Enterprise that she was “horrified” by what took place. “When you protect the things you believe in with your body, it changes you for good. It radicalizes you for good,” Ms. Koster said.

In the wake of what it called police violence, an association that represents some Davis faculty members called for Ms. Katehi’s resignation on Saturday. In a letter that was published online, Nathan Brown, an assistant professor in the English department and a member of the association’s board, said that Ms. Katehi was responsible for the violence and should resign immediately.

“The fact is: the administration of U.C. campuses systematically uses police brutality to terrorize students and faculty, to crush political dissent on our campuses, and to suppress free speech and peaceful assembly. Many people know this,” Mr. Brown wrote. “Many more people are learning it very quickly.”