The Washington, D.C., riots of 1968 were a four-day period of violent civil unrest and rioting following the assassination of leading African American civil rights activist Martin Luther King Jr., on April 4, 1968. Part of the broader King-assassination riots that affected at least 110 U.S. cities, those in Washington, D.C.—along with those in Chicago and Baltimore—were among those with the greatest numbers of participants. President Lyndon B. Johnson called in the National Guard to the city on April 5, 1968 in order to assist the police department in quelling the unrest. Ultimately, 13 people were killed, with approximately 1,000 people injured and over 6,100 arrested.