(CNN)Here's some background information about violence against US politicians and diplomats throughout history.
January 30, 1835 - President Andrew Jackson is shot at by Richard Lawrence as he attends a congressional funeral in the Capitol in Washington. Lawrence fires twice, but the bullets do not discharge.
February 15, 1933 - Chicago Mayor Anton Cermak is killed in Miami, with a bullet meant for President-elect Franklin D. Roosevelt. He dies on March 6.
August 28, 1968 - US Ambassador to Guatemala John Gordon Mein is killed by guerrillas in Guatemala City, Guatemala.