SAN FRANCISCO — Viral videos of riot police repeatedly pepper spraying a row of seated, non-violent Occupy Wall Street protesters at a California university has sparked outrage, an investigation and calls for the college chancellor’s resignation.

It also set off a debate about how far officers can and should go to disperse peaceful demonstrators.

While many students, lawmakers and even the university’s chancellor saw the officers’ actions as excessive, some experts on police tactics say, depending on the circumstances, pepper spray can be a less violent crowd control measure than dragging protesters away or swinging at them with truncheons.

“Between verbalized commands and knock-down, drag-out fights, there’s quite a bit of wiggle room,” said David Klinger, a former Los Angeles Police Department officer and instructor at the University of Missouri-St. Louis who reviewed the pepper spray footage.

“When you’ve got a bunch of people who are clearly noncompliant, locking arms, it doesn’t look good [on camera],” he said.

Soon after the incident on Friday at the University of California, Davis, video recordings spread across the Internet.

Images of the officer seen spraying the protesters became the subject of a blog, which featured him spraying famous figures, from Gandhi to John F. Kennedy.

The university announced Monday that it has placed the police chief and two officers on administrative leave to restore trust and calm.

Still, nearly 2,000 students and residents gathered at the main quad to hear speeches and chant slogans against police and university officials. Students who were pepper-sprayed opened the protest, saying they felt unsafe on campus with the chancellor in power.

“We were just kids sitting down in a circle singing,” said student David Buscho, 22, of San Rafael, Calif. “It felt like hot glass … I was paralyzed with fear.”

Pepper spray is an inflammatory agent that derives its active ingredient from chili peppers. When the spray is deployed, it causes nearly instant inflammation, resulting in dilation of the capillaries in the eyes, paralysis of the larynx and a burning sensation on the skin.

Buscho said students were yelling at police Friday that they were peacefully protesting. One of the helmeted officers began pointing a spray can directly at protesters’ faces, he said.

“I had my arms around my girlfriend. I just kissed her on the forehead and then he sprayed us,” he said. “Immediately, we were blinded … He just sprayed us again and again and we were completely powerless to do anything.”