He also delivered miraculous news: that U.S. Representative Gabrielle Giffords, 40, who received a bullet wound to the head that traveled the length of her brain on the left side, "opened her eyes for the first time." He repeated the statement several times, as if to let its significance about her condition sink in.
The President added that, no matter how long it may take, the country will be with Giffords "every step of the way" as she makes her recovery. "She knows we are here, she knows we love her and she knows we are rooting for her," he said.
When the President made his announcement, all 26,000 people in the hall, including Michelle Obama, who held the arm of Giffords's husband, NASA Shuttle Commander Mark Kelly, rose to their feet for a prolonged ovation. Most of them, including Mrs. Obama, also wiped away tears – a gesture repeated only moments later, when Kelly and Daniel Hernandez, the 20-year-old intern credited with saving the life of Rep. Giffords, embraced after the President's introduction.
Before his speech, President Obama stopped at Tucson's University Medical Center to pay his respects to Giffords, as well as visit four other patients wounded on Saturday. He also met the families of those killed, including the parents of 9-year-old Christina Taylor Green, to whom his speech paid special tribute.
"When a tragedy like this strikes, it is part of our nature to demand explanations – to try to impose some order on the chaos, and make sense out of that which seems senseless," Obama said in his speech.
"Already we've seen a national conversation commence, not only about the motivations behind these killings, but about everything from the merits of gun safety laws to the adequacy of our mental health systems. Much of this process, of debating what might be done to prevent such tragedies in the future, is an essential ingredient in our exercise of self-government.
"We must examine all the facts behind this tragedy," the President continued. "We cannot and will not be passive in the face of such violence. We should be willing to challenge old assumptions in order to lessen the prospects of violence in the future. But what we can't do is use this tragedy as one more occasion to turn on one another."
Of Christina Taylor Green, he said, "She saw all this through the eyes of a child, undimmed by the cynicism or vitriol that we adults all too often just take for granted. I want us to live up to her expectations. I want our democracy to be as good as she imagined it."
He added, "If there are rain puddles in heaven, Christina is jumping in them today. And here on Earth, we place our hands over our hearts, and commit ourselves as Americans to forging a country that is forever worthy of her gentle, happy spirit."