President Barack Obama has proclaimed the days leading up to Sept. 11 as National Days of Prayer and Remembrance.

"I ask that the people of the United States honor and remember the victims of September 11, 2001, and their loved ones through prayer, contemplation, memorial services, the visiting of memorials, the ringing of bells, evening candlelight remembrance vigils, and other appropriate ceremonies and activities," Obama said in a statement. "I invite people around the world to participate in this commemoration."

Nearly 3,000 people from all over the world died in the attacks on the World Trade Center and the Pentagon on Sept. 11, 2011.

President Obama said despite the grief, America came together.

"No matter where we came from, what God we prayed to, or what race or ethnicity we were, we were united as one American family," Obama said. "As we honor the memory of those we have lost, let us summon that spirit once more. Let us renew our sense of common purpose. And let us reaffirm the bond we share as a people: that out of many, we are one."

The president also praised the more than 2 million American service members who have gone to war since the attacks.

"As we mark these solemn days, we pay tribute to the men and women who made the ultimate sacrifice in faraway lands, to heroes who died in the line of duty here at home, and to all who keep faith with the principles of service and sacrifice that will always be the source of America's strength," he said.

Several memorials across the country will take place on Sept. 11.

In New York, four moments of silence will be observed to commemorate the times when each plane hit and each tower fell, starting at 8:46 a.m.

At sunset, the "Tribute in Light" will illuminate the skies above New York City for the night. The illuminated memorial reaches 4 miles into the sky and is the strongest shaft of light ever projected from earth into the night sky.

In his weekly address, the president paid tribute to those who lost their lives and honored the first responders who fought to save them.

"On that clear September morning, as America watched the towers fall, and the Pentagon burn and the wreckage smoldering in a Pennsylvania field, we were filled with questions," Obama said. "Where had the attacks come from, and how would America respond? Would they fundamentally weaken the country we love? Would they change who we are?"