The shots came from the crowd outside the Washington Hilton that drizzly afternoon -- six shots that would show the nation once again how vulnerable to attack its presidents are.

President Ronald Reagan, then 70, a Washington newcomer in office two months, had paused to wave to the knot of people. At the sound of the shots, Secret Service agents shoved him into the presidential limousine and sped away, not realizing he had been hit. Three men lay wounded, one with blood dripping from his head, and the young assailant, whose mission would soon be revealed, was quickly restrained.

Twenty-five years ago today, the nation watched in shock as television brought home again and again the reality of the shooting. It was a moment chilling in its possibilities, reminding Americans another time in two decades that a national tragedy is only an assassin's bullet away. People saw once again that they live in an epicenter of power, where monumental shifts can occur in an instant.

For some, it was a day that forced them to walk alongside history, to participate in the urgent events that unfolded. Some of them were with the president at his most unguarded moments. They saw his attempts to be strong and his sense of humor. They overheard the "Honey, I forgot to duck" quip he delivered when his wife, Nancy, arrived at the hospital. They revisit their memories of this historic episode from time to time. One of them, who suffered a severe head injury, has had to live with the imprint of that day.

Some say they will always be haunted by what could have happened.