California Highway Patrol officials are defending a plainclothes officer who pointed his gun at Oakland protesters after they learned he and his partner were police.
The officer drew his weapon Wednesday night after he was assaulted during demonstrations against the killings of black men by white officers, authorities said.
While standing behind the officer, CHP officials also revealed they have created phony Twitter accounts and dressed like demonstrators to do surveillance.
The San Francisco Bay Area has seen regular protests in the past week over two recent grand jury decisions to not indict white officers who killed unarmed black men in Ferguson, Missouri, and New York.
In Berkeley, demonstrations have drawn hundreds of people who have sometimes clashed with police as they blocked highways, smashed windows and refused police orders. Several hundred people have been arrested, and both police and protesters have been injured at the marches.
The protests have gotten smaller over the last day with a massive storm hitting the Bay Area.
On Wednesday night, the officers got out of their car in downtown Oakland after protesters smashed store windows, The Oakland Tribune reported. They followed them for many blocks before about 150 marchers identified the two as possible officers and alerted others.
Protesters pulled off a dark handkerchief tied around one officer's face then struck him in the head.
Highway patrol officials maintain the officer's actions were necessary to defend himself and his partner against an unruly crowd.
The officer's name was not released. CHP Golden Gate Division Chief Avery Browne said the two officers' actions will be investigated but they remain on duty.
The brief melee was captured by freelance news photographers. The protester who struck the officer was arrested by Oakland Police.
National Lawyers Guild Executive Director Carlos Villarreal told the Tribune the incident is doubly troubling because earlier in the week highway patrol officers, attempting to clear a blocked highway, fired bean bags from a freeway overpass at protesters below.
He said the agency has acted “recklessly.”