RELATED SLIDESHOW: Images of the 9/11 attacks
Speaking under a dull gray sky in a field near Shanksville to mark the eighth anniversary of the Sept. 11 attacks, Powell said the choice was clear for the passengers and crew of the plane taken over by four suicidal fanatics.
"They refused to let it just happen," Powell said of the passengers, who learned of the other highjackings on Sept. 11, 2001, and decided to act.
"In place of fear ... they found the courage to act," Powell said.
Former Homeland Security Secretary Tom Ridge and retired General Tommy Franks were also among those to remember those who perished.
Flight 93 was traveling from Newark, N.J., to San Francisco when hijackers took it over with the likely goal of crashing it into the White House or Capitol. The passengers and crew hatched a plan to storm the cockpit after learning of the coordinated attacks, and the 9/11 Commission concluded that the hijackers downed the plane in Pennsylvania as the hostages revolted.
Powell said thousands of other lives were saved because the passengers and crew fought back.
Several hundred people attended the event, but busloads of visitors continued to arrive through the morning and into the afternoon.
Families of Flight 93 president Gordon Felt, whose brother was aboard Flight 93, told visitors that the victims chose to be courageous and that their loved ones are thankful for it.
Ridge, who was the governor of Pennsylvania at the time of the attacks, said eight years later we still ask why something so "brutally senseless" happened that day. He said the reason was too profound to truly understand but we must "honor the day lives were saved and heroes were made over the skies of Shanksville."
Many of the speakers mentioned the efforts to erect a memorial in time for the 10th anniversary of the attacks. The $58 million memorial will cover an area of 2,200 acres.
Franks said the memorial would remind future generations of the character revealed through the adversity faced by the passengers and crew.
"Their lives were not taken, their lives were given," Franks said.