Source: http://memory.loc.gov/ammem/today/sep02.html

On September 2, 1885, a mob of white coal miners violently attacked their Chinese co-workers in Rock Springs, Wyoming. Twenty-eight Chinese were killed and fifteen wounded, some of whom later died. The homes of seventy-nine Chinese people were set ablaze and the bodies of many of the dead and wounded thrown into the flames. Hundreds of Chinese workers fled into the surrounding desert. Violence exploded after Chinese workers refused to participate in a strike for higher wages planned by Euro-American miners. A week later, federal troops escorted Chinese laborers back to the mines. After restoring order, federal troops remained at Rock Springs until 1898. Although the federal government refused responsibility for actions in a territory, President Grover Cleveland requested a compliant Congress to indemnify the Chinese for $150,000.

but take a look at all the race related riots in the United States’ history:
en.wikipedia.org/wiki/Mass_racial_violence_in_the_United_States which links to related external documented sites