By Sunlen Miller and John Parkinson:

Hundreds of Members of Congress gathered on the East Front steps of the Capitol late this morning to sing an emotional rendition of "God Bless America," to mark the eleventh anniversary of the September 11, 2001 terrorist attacks.

The annual Congressional tradition, to sing together on the steps of the Capitol, is a recreation of the moment when they first spontaneously sang the patriotic song the night of Sept. 11 in 2001 to show unity in the face of despair that day.

This year, lawmakers sang along as the Marine Corps Band performed the "Star Spangled Banner" and "God Bless America."

Leaders of both the House and Senate paid tribute, especially to the courage of the passengers on board United Flight 93, which crashed in Shanksville, Pa., noting that the flight was headed to the Capitol building.

Speaker of the House John Boehner, R-Ohio, choked up as he called those passengers "patriots who banded together in the sky over Shanksville to save this Capitol and these steps. Today we listen, and vow to never forget," he said.

"To celebrate the greater good that comes from serving one another and standing shoulder-to-shoulder, and to carry on, come what may, to meet the unmet challenges and complete the unfinished work. For we are Americans, and this is our place."

Each member gathered on the steps held a tiny American flag, some tucked into the pockets of their jackets, and others waving them in the air, as the leaders spoke with common themes of unity, resolve, and patriotism.

"The memories of that dark day in our shared history are painful, but they give me hope as well," Senate Majority Leader Harry Reid, D-Nev., said. "On September 11th, and during the difficult months that followed, Americans showed the world how a unified nation can fight back against darkness and fear. In the face of great evil, so many rushed forward to show great courage, dignity and kindness."

Senate Minority Leader Mitch McConnell, R-Ky., said that the day ended up revealing the "greatness" of the nation. "We remember how worried some people were about what the attacks would do to America," McConnell said, " Would it weaken us in the world? Would it weaken us at home? Would we stand up? Would we shrink? Well, 11 years later we can say with certainty and pride that 9/11 didn't reveal the weakness of America. It revealed the greatness of America."

Minority Leader of the House, Nancy Pelosi, D-Calif., said that the day should serve as a reminder to "always give voice to those silenced forever 11 years ago; and to draw inspiration from the families of the victims."