Congressman James M. Hinds (R-Arkansas) was shot and killed October 22, 1868 by George A. Clark, a member of the Ku Klux Klan.
Senator Huey Long (D-Louisiana) was shot September 8, 1935 and died two days later. It is disputed as to whether Carl Weiss assassinated Long or if Long's bodyguards accidentally shot Long and framed Weiss.
Senator Robert F. Kennedy (D-New York) was shot by Sirhan Sirhan June 5, 1968 after giving a speech at The Ambassador Hotel in Los Angeles. Kennedy, who was campaigning for the Presidency at the time, died early the next morning.
Congressman Leo Ryan (D-California) was assassinated in Guyana during an official visit to investigate allegations of abuse of American citizens at the Jonestown compound of the Peoples Temple religious organization in 1978.<3>
Congressman Larry McDonald (D-Georgia) was killed September 1, 1983 in the Korean Air Lines Flight 007 incident when a Soviet interceptor shot down the passenger plane he was on.
http://en.wikipedia.org/wiki/United_States_Congressmen_wounded_or_killed_in_the_line_of_duty