Two officers from the US Federal Protective Service received gunshot wounds during riots in Oakland, California, caused by the murder of African American George Floyd by police in Minneapolis.
One of the officers has died due to injury, CNN reported.
An investigation is underway in this regard.
According to the city police department, at least 7,500 protesters took to the streets.
Protesters caused significant damage to the city.
Hundreds of people rallied outside the White House, which was briefly put under lockdown on Friday, demanding justice over the death of George Floyd.
Minnesota, New York, Atlanta, and other regions have seen violent unrest.
A former Minneapolis police officer has been arrested and charged with murder over Floyd's death in custody. Derek Chauvin, who is white, was shown in footage kneeling on 46-year-old Floyd's neck on Monday. He and three other officers have since been sacked. Chauvin, 44, is due to appear in court in Minneapolis for the first time on Monday.