The FBI’s San Francisco field office said in a statement that the officer, Dave Patrick Underwood, 53, died after someone fired at him from a vehicle.
A second officer who was with Underwood was injured in the Friday night shooting at the Ronald V. Dellums Federal Building in downtown Oakland, the FBI said. That officer has not been identified nor have any suspects.
The officers were working for the Federal Protective Service, an agency within the Department of Homeland Security that tries to prevent terrorism and other criminal acts from threatening government infrastructure.
Acting Department of Homeland Security Secretary Secretary Chad Wolf said Saturday that an “assassin cowardly” shot the officers while they "stood watch over a protest."
The department’s deputy acting secretary, Ken Cuccinelli, added that targeting federal buildings and police officers with an “intention to do harm and intimidate...is an act of domestic terrorism.”
The FBI said Sunday that it had not yet determined a motive.
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The shooting occurred as people took to the streets in cities across the United States to protest the killing of George Floyd by Minneapolis police officer Derek Chauvin, who has been charged with third-degree murder. The events sometimes turned violent, with people torching buildings and clashing with authorities.
In Oakland, thousands turned out for a protest that began peacefully but turned violent late Friday, NBC Bay Area reported.