Armed security guards working for anti-abortion protesters pepper sprayed counter-demonstrators in an ugly confrontation caught on tape Tuesday in Northern California.The melee unfolded outside of Planned Parenthood in Walnut Creek, about 25 miles east of downtown San Francisco, where anti-abortion protesters regularly form a picket line."It was like a war zone out there," said Trevor Henrich, a 28-year-old Walnut Creek resident and freelance photographer who was sprayed while taking pictures of the protest. "I was shocked that it happened."Lacey Brown, a 25-year-old real estate agent and regular counter-demonstrator, said she had never seen the protesters bring their own security guards — who had guns and pepper spray — prior to Tuesday."It's never gotten physical before," Brown told NBC News on Wednesday. "The issue was they were saying, 'No you can't come on to the sidewalk' and we were like, 'Um it's a public sidewalk, you can't tell anyone where to go.'"Brown said she was among four people who were sprayed and she posted video of the confrontation to Facebook. The spraying appeared to be touched off when one counter-demonstrator kept pointing at an insignia on a security guard's uniform."I want them to get arrested, that was assault and battery," Brown said. "The security guard said my friend was reaching for his gun, but there's video to show that's not what happened."The anti-abortion protesters said the guards were provided by 40 Days For Life, a group based out of College Station, Texas, that seeks to "end the injustice of abortion."The group's CEO and president, Shawn Carney, confirmed to NBC News that 40 Days For Life hired guards in that Walnut Creek protest.He claimed the anti-abortion protesters were being confronted by aggressive counter-demonstrators with bullhorns in the days and weeks prior to the Tuesday incident.“People were just standing there praying with their rosary and being harassed," Carney said.A spokesman for the Contra Costa County District Attorney's Office said the matter is being investigated by city police and declined further comment."The City of Walnut Creek and its Police Department take seriously the right of people to peacefully protest, regardless of the position protestors hold," according to a City Hall statement on Wednesday. "The City and PD also support the right of people to seek safe access to health care facilities, and will work to ensure the safety of patients, protestors and counter-protestors alike."