(CNN)Racist emails -- like one that depicted President Obama as a chimpanzee -- resulted in three Ferguson, Missouri, city employees resigning or being fired, the city spokesman said Friday. Police officers Capt. Rick Henke and Sgt. William Mudd resigned Thursday over the emails discovered during the U.S. Department of Justice investigation of racial prejudice in the city's police and judicial system, city spokesman Jeff Small said on Friday, citing the city attorney. The city's top court clerk, Mary Ann Twitty, was fired earlier this week in connection with the emails, Small said. Several employees forwarded the emails but until now none had been disciplined, the report said. Examples of the racist emails include one sent in October 2011 that showed a photo of bare-chested dancing women, apparently in Africa, with the caption "Michelle Obama's High School Reunion." A June 2011 email described a man trying to put his dogs on welfare because the canines were "mixed in color, unemployed, lazy, can't speak English and have no ... clue who their Daddies are." Some critics have called for the department to be disbanded and for Police Chief Thomas Jackson to resign. In a Friday interview with CNN's Sara Sidner, Ferguson Mayor James Knowles said Jackson was not copied on any of the emails. When asked if Jackson and the city manager may be fired, Knowles said, "We're going to do our due diligence and hold people accountable." Knowles also said he doesn't think the department will be disbanded. When asked about what happens next in Ferguson, U.S. Attorney General Eric Holder said Friday, "We are prepared to use all the power that we have, all the power that we have to ensure that the situation changes there. And that means everything from working with them to coming up with an entirely new structure." When a reporter asked if that included dismantling the police force, Holder replied, "If that's what's necessary then we are prepared to do that." Holder ordered the investigation after a white police officer, Darren Wilson, shot and killed black teenager Michael Brown last summer, setting off months of sometimes violent street protests in the town outside St. Louis. The DOJ declined to bring charges against Wilson, who has since left the force. No state charges were filed either. In a separate report, the Justice Department described what it said was a "pattern and practice" of discrimination against African-Americans by the Ferguson police and municipal courts. That discrimination included racist emails. Ferguson is a town of 21,000 that is 67% African-American. Among the findings in the report: . From 2012 to 2014, 85% of people subject to vehicle stops by Ferguson police were African-American, 90% of those who received citations were black, and 93% of people arrested were black. In 88% of the cases in which Ferguson police officers reported using force, it was against African-Americans. From 2012-2014 black drivers were twice as likely as white drivers to be searched during traffic stops, but 26% less likely to be found in possession of contraband. President Obama said Friday that although he doesn't think the abuses of power in Ferguson are typical of America, there are individuals and possibly whole departments in American law enforcement that may struggle to prevent prejudice in their ranks. "I don't think that is typical of what happens across the country, but it's not an isolated incident," Obama said in an early morning interview on SiriusXM's Urban View channel. "I think there are circumstances in which trust between communities and law enforcement has broken down, and individuals or entire departments may not have the training or the accountability to make sure they are protecting, serving all people, and not just some." Knowles has outlined a number of reforms the city implemented to address some of the Justice Department's concerns, and said the city "must do better" to address racism. "We must all work to address issues of racial disparity in all aspects of our society," he said Wednesday. Ferguson police chief mum on federal report . CNN's Sara Sidner contributed to this report.
2 Ferguson police officers resign over racist emails, city spokesman says . Earlier this week, the city's top court clerk was fired over the emails, spokesman says .