"Hi, this is the captain. I would like you all to remain seated. There is a bomb on board and we are going back to the airport ... Please remain quiet." -- Hijacker aboard United Flight 93, which crashed near Shanksville, Pennsylvania.

"We may have a hijack. We have some problems over here right now." -- Air traffic controller on the ground on Long Island shortly after the first plane struck the north tower.

A white rose is seen at the National September 11 Memorial & Museum in New York Jan. 23, 2015. 

"Tonight, I ask for your prayers for all those who grieve, for the children whose worlds have been shattered, for all whose sense of safety and security has been threatened. And I pray they will be comforted by a power greater than any of us, spoken through the ages in Psalm 23: 'Even though I walk through the valley of the shadow of death, I fear no evil, for You are with me.' " -- President George W. Bush on Sept. 11, 2001.

"This mass terrorism is the new evil in our world today. It is perpetrated by fanatics who are utterly indifferent to the sanctity of human life, and we, the democracies of this world, are going to have to come together and fight it together." -- British Prime Minister Tony Blair on Sept. 11, 2001.

"Commending the victims to almighty God's mercy, I implore his strength upon all involved in rescue efforts and in caring for the survivors." -- Pope John Paul II on Sept. 11, 2001.

“Today, our fellow citizens, our way of life, our very freedom came under attack in a series of deliberate and deadly terrorist acts. The victims were in airplanes or in their offices: secretaries, business men and women, military and federal workers, moms and dads, friends and neighbors. Thousands of lives were suddenly ended by evil, despicable acts of terror. The pictures of airplanes flying into buildings, fires burning, huge -- huge structures collapsing have filled us with disbelief, terrible sadness and a quiet, unyielding anger. These acts of mass murder were intended to frighten our nation into chaos and retreat. But they have failed. Our country is strong. A great people has been moved to defend a great nation.”  --President George W. Bush on Sept. 11, 2001.