The United States will mark the 14th anniversary of the 2001 terrorist attacks that claimed the lives of nearly 3,000 people Friday with memorial events reflecting grief, loss and anger. On Sept. 11, 2001, al Qaeda terrorists hijacked four passenger planes, crashing them into the north and south towers of the World Trade Center in New York City, the Pentagon in Virginia and a field in Pennsylvania.

Sept. 11, 2001, brought Americans closer, however briefly, as many looked to one another for strength, courage and comfort. Below are some of the most memorable quotes that capture the array of emotions that day and in its aftermath.  

"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.

GettyImages-462016828 A white rose is seen at the National September 11 Memorial & Museum in New York Jan. 23, 2015. Photo: Getty Images

"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.

“If we learn nothing else from this tragedy, we learn that life is short and there is no time for hate.” -- Sandy Dahl, wife of Flight 93 pilot Jason Dahl, in Shanksville, Pennsylvania, in 2002.

“Remember the hours after Sept. 11 when we came together as one ... It was the worst day we have ever seen, but it brought out the best in all of us.” -- Then-U.S. Sen. John Kerry in 2004.

GettyImages-180305590 Rows of American flags are placed along the south pool of the 9/11 Memorial during ceremonies for the 12th anniversary of the terrorist attacks, Sept. 11, 2013, in New York City. Photo: Getty Images

"My older brother John lived [his life] in Technicolor. ... When he walked in the door, the whole house lit up. And I’m sure heaven lit up when he got there too.” -- Anthoula Katsimatides at the World Trade Center site in 2005.

“One of the worst days in America’s history saw some of the bravest acts in Americans’ history. We’ll always honor the heroes of 9/11. And here at this hallowed place, we pledge that we will never forget their sacrifice." -- President George W. Bush at the Pentagon in 2008.

“Sept. 11, 2001, seems destined to be the watershed event of our lives and the greatest test for our democracy in our lifetimes.” -- Lt. Col. Shelton F. Leskford, U.S. Marine Corps, in 2008.