Moments after the crackle of gunfire echoed off the stone wall outside the hotel, an eyewitness said, "I knew it was more than just firecrackers."

It was an unnecessary remark. Within minutes Americans everywhere knew it had happened again -- another president shot, another political promise interrupted by violence.

There was no way to escape this replaying of the old national horror. Over and over, hour after hour, in slow motion, in stop action, and in all the other modern techniques of electronic communications, television brought home the latest installment of a continuing American tragedy.

And once again it was all too familiar: the sudden pap-pap-pap of gunfire, the bodies hurting to the ground, the hoarse shouts, the presidential limousine speeding off to the hospital emergency room, the gathering of the slient crowds outside, the news bulletins of the president's condition coming furiously throughout the day, the clusters of people huddled before their TV sets again forced to think the unthinkable.

We're all been through this before. Those television acenes yesterday formed inseparable parts of an unending spasm of violence that has struck the nation blow after blow.

For a generation violent acts have disrupted the political process, torn at the nation's leadership and left citizens numbed by the seemingly inexorable cycle of terror. For a generation Americans have learned to live with the knowledge that the leaders in whom they place their greatest trust and hope may be removed suddenly and violently.

The violence has struck down leaders regardless of ideology or race. It has aimed at public figures of all political persuasions. It has destroyed liberals and consevatives, Democrats and Republicans, blacks and whites. The only common denominator seems to be a collective madness that repeatedly strikes at the top.

What we witnessed yesterday evoked vivid national memories of other days of violence -- of the shooting of the kennedy brothers in Dallas and Los Angeles, of Lee Harvey Oswald in the basement of the police station, of Martin Luther King Jr. in Memphis, of Malcolm X in Harlem, of George Wallace in suburban Maryland, of the two assassination attempts on Gerald Ford's life.

The bullet that wound President Reagan, on a sodden spring day in Washington, once more struck a political leader who stood at the peak of his powers. In Reagan's case, especially, the shooting came at a a moment of unusual political activity that centered on the president's dramatic attempt to change the direction of the national government.

He has set forward for national debate an economic program that, if enacted, would restructure the way the federal government operates. His attempt to turn back federal powers to the states and local communities represents to profound shift in governmental priorities. His foreign policy initiatives signal a sharp break with policies of his immediate presidential predecessors.

Not for half a century has a new president moved forward so aggressively on so many disparate political fronts. Debate over Reagan's bold program was still in a preliminary stage when he was shot.

This sense of another presidential beginning being shockingly halted by violence was also depressingly familiar. The violence that has taken so many American leaders has left a collective legacy of unfulfilled political promises. And among countless Americans it has created a haunting form of morbid introspection, of hopes dashed, of wondering what might have been, as they have seen their leaders struck down again and again.

No one can say with any cetainty precisely what impact this series of violent acts has had on individual Americans, or on the country as a whole. But obviously, in this age of instant video communications, it has been great. Once more, America sat in front of the television, waiting anxiously for news bulletins, wondering what is happening to our country.

Never in American history has violence claimed so many national leaders over so long a period. Never, largely because of television's special capacity to reach intimately into homes across the country simultaneously, have so many Americans participated personally in so many national tragedies.

The wonder is that the citizens and their country have proved so resilient, in the face of this succession of assults on national stability.

But each of these shocks breeds its own reactions; the line between national resilience and national recrimination inevitably becomes increasingly strained. Equally inevitably, maintaining national stability -- or security -- becomes a more paramount national concern.

And a great question remains unanswered: Just how much more of this tearing at the fabric of the nation can American endure without fundamentally changing the character of national life?

Ronald Reagan was elected, in part at least, on the hope that he would usher in a new era of national unity and strength after a long series of national failures and frustrations. Now his presidency, and that hope, has been overtaken by the same nightmarish scenes that the country has lived through before.

As the news pours into homes, in fragmentary and confusing fashion, hope remains -- that this latest act of violence will not mark yet another tragic break in political leadership. Reagan, in a paraphrase of Jack Dempsey's famous remark after lossing his heavyweight crown, is said to have told his wife, "Honey, I forgot to duck."

The hope is that Reagan's sense of American good humor in the face of adversity, the celebration of the survivor, will be what is most remembered about the events of March 30, 1981. But it won't begin to answer why the violence occurs -- or what to do about it.