Editor's note: David Gergen is a senior political analyst for CNN and has been an adviser to four U.S. presidents. He is a professor of public service and director of the Center for Public Leadership at the Harvard Kennedy School.

(CNN) -- Until we have more definitive information about the shooter, pointing fingers at who might bear responsibility for the Tucson, Arizona, massacre only contributes to what we must end in America: a toxic political environment.

Soon after the news broke, the internet lit up with accusations, even before we knew anything at all about the man who pulled the trigger. Much of the early commentary, especially from the left, blamed the Tea Party, Sarah Palin, Glenn Beck, etc. for employing a rhetoric of militarism and creating a climate of hate.

Commentators from the right soon retaliated, arguing that the left was just as guilty of rhetorical excess and through bad governance, had inspired a citizen revolt. As of this hour, we have a country that is not only deeply saddened but even more divided than we were before the shooting.

We can do better -- a lot better.

My experience in government is that typically, a lot of what we think we know in the first hours of a calamitous event turns out to be wrong. In the White House Situation Room just after President Reagan was shot, we were first informed that press secretary Jim Brady had died; we said a prayer. Later we learned that he had miraculously survived; we said another prayer. It took even more time to figure out whether the would-be assassin John Hinckley was a loner or what his motivations were. Even now we are still unsure about what prompted his madness.

As a young man, I was struck by how quickly, after Lee Harvey Oswald had murdered President Kennedy, speculation centered on whether Oswald was acting on behalf of the right-wing John Birch Society. Instead, we learned that he was tied to Fidel Castro.

The country would be well served now if we cooled the accusations until we learn more about the man police are holding in Tucson, Jared Loughner. He appears to be mentally unhinged, someone who has threatened others. Why he targeted one of the most admired and popular political leaders in Arizona is unclear.

None of this is to excuse the climate of hatred that has built up in the United States over our politics and our politicians. Its origins go back a long time, but it has undeniably grown worse in recent years -- during the George W. Bush years, when the left was intensely alienated, and now during the Obama years, when the right has become vitriolic.

During the 2008 campaign, many of us in the "commentariat," including me, openly worried that occasional calls for violence at Palin rallies would lead to bloodshed. To his credit, Sen. John McCain eventually stepped in and called a halt. Since Obama's inauguration, there have been many signs that threats to public officials have been rising.

All of this should be the subject of renewed "soul-searching", as Pima County Sheriff Clarence Dupnik called for in the midst of the carnage. So should the continued, easy access to guns in this country -- something we have fretted about for years but haven't resolved. How can it be that a young man with so many signs of derangement as Loughner could purchase a very dangerous 9 mm Glock handgun less than a month ago -- and legally?

Too many times in our history, assassins have struck down our leaders with guns. Four presidents have died at the hands of gunmen -- Lincoln, Garfield, McKinley and Kennedy. Four other presidents have narrowly escaped -- FDR, Truman, Ford and Reagan. Gunmen have also taken the lives of some who have served in Congress.

And now we have Gabrielle Giffords, apparently the first female member of Congress who has been shot, courageously fighting for her life. Six others are dead. This is not a moment to point fingers and make accusations. But it is a time to pray for the victims -- and to pledge to each other that we will struggle for a more civil and decent America.

The opinions expressed in this commentary are solely those of David Gergen.