Tulsa police officer Betty Shelby was found not guilty on Wednesday in the 2016 shooting death of 40-year-old Terence Crutcher, ABC News reported.
Protesters gathered after the verdict to demonstrate peacefully, chanting "No justice, no peace" and "Hands up, don't shoot."
Oklahoma Gov. Mary Fallin appealed to citizens for peace after the verdict. "Those who disagree with the verdict have the right to express their opinions; I just ask that they do so in a peaceful manner," she said.
"We are deeply disappointed that yet another police officer has eluded conviction for killing an unarmed African-American. We eagerly await the findings of the Department of Justice's investigation, and hope that federal charges will be filed given the egregious misconduct," said NAACP Legal Defense Fund President Sherrilyn Ifill in a statement.
Crutcher's death was one of a spate of highly-publicized police officer-involved shooting deaths of unarmed black men in the United States in recent years.
Shelby's acquittal angered many on social media.