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.

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.

I was the only one who had a chance to do anything,” Clint Hill said. “The way everything developed, the way all the other agents were positioned, I was the only one who had a chance to get to the car and do anything.