A US Secret Service agent who leapt on to John F Kennedy's limousine as it came under fire in Dallas, and was pictured in famous photos of one of the most dramatic events in US history, has died at the age of 93.

Clint Hill, the Secret Service agent who jumped onto the back of the limousine moments after shots rang out in Dealy Plaza. Those who knew him tell CBS News Texas that Hill never really overcame the guilt he felt on that tragic day.

Clint Hill, the Secret Service agent who leaped onto the back of President John F. Kennedy's limousine after the president was shot, then was forced to retire early because he remained haunted by memories of the assassination, died Friday. He was 93.