U.S. Representative Gabrielle Giffords led a crowd in the Pledge of Allegiance, her words ringing out across a cold Tucson night in a rare public appearance Sunday evening at a candlelight vigil one year after surviving a deadly shooting that killed six.

The Democratic congresswoman stepped onstage to cheers from the crowd. Ron Barber, a staffer who was wounded in a deadly shooting one year ago, invited her to lead the audience in the pledge.

Mark Kelly leans on the shoulder of his wife, U.S. Rep. Gabrielle Giffords, at a TUcson memorial vigil remembering the victims and survivors of the Tucson shooting that wounded Giffords, 12 others and killed six one year ago Sunday. (Ross D. Franklin/Associated Press)

The crowd chanted: "Gabby, Gabby."

She limped to the podium, and husband Mark Kelly helped lift her hand over her heart. After a year in which she has struggled to speak, Giffords recited the pledge with the audience, head held high and a smile on her face as she punched each word.

The remembrance at the University of Arizona capped off a day of events, including a church service that drew hundreds in the afternoon and a citywide bell-ringing at 10:11 a.m., the exact time a gunman started shooting at a Safeway political event.

With hugs and tears, southern Arizonans remembered the dead, the shattered lives and those who acted heroically after a gunman opened fire at an outdoor meet-and-greet that severely wounded Giffords and killed six.

"Those of us who survived were forever changed by that moment," Kelly said. "For the past year, we've had new realities to live with, the reality and pain of letting go of the past.

"There's a reality that life is unpredictable, and that even in the best of times, our cherished friends, the good, the caring, the innocent among us, the closest and dearest people we know, can be taken from us," he said.

Bells chime for victims

The day of remembrance began with the ringing of church bells and hand-held bells throughout the city at 10:11 a.m., the exact time the gunman shot Giffords in the head and methodically moved down a line of people waiting to talk to her during a public event outside a Safeway supermarket on Jan. 8, 2011.

Relatives of the six dead walked solemnly down the aisle with a single red rose, placing the flowers in a vase in front of a picture of a heart.

Mark Kelly hugs his wife, U.S. Representative Gabrielle Giffords, who was shot in the head. (David Lienemann/White House/Reuters)

Hundreds of people packed a Tucson cathedral earlier Sunday for a service to remember the bloody morning one year ago when a gunman's deadly rampage shook a community and shocked a nation.

Girls in white dresses and red sashes danced down the aisle as a song called Hero in the Dark played, and a pastor called on everyone to celebrate the lives of the people lost and those who acted heroically during the shooting that left six dead and 13 wounded, including Giffords.

The names of those killed were read as a bell rang for each of them, and their family members and survivors walked down the aisle with red roses and placed them in a vase at the front of the church.

"We remember, we remember, we remember with grateful hearts," those gathered chanted together, standing, many closing their eyes.

Girl, 9, among victims remembered

"Even in the midst of this troubling year, the healing, the courage that we have experienced in our community — each one of us can notice how our cups overflow with the blessings of our lives," said Stephanie Aaron, Giffords' rabbi.

Ron Barber, a Giffords staffer who survived two gunshot wounds, said he woke up Sunday dreaming about Giffords, who was severely wounded, and Giffords staffer Gabe Zimmerman, who died.

'It's good for us to be honest and admit it's not easy remembering this day.'—Rev. Andrew Ross

"You have to think about the six people whose loved ones don't have them today," said Barber at St. Augustine Cathedral just before the service began. In the crowd were survivors, families and others, including Arizona Gov. Jan Brewer.

Among those killed were a federal judge and nine-year-old Christina-Taylor Green, born on Sept. 11, 2001.

Many throughout the close-knit southern Arizona community began the day of remembrance Sunday by ringing bells at 10:11 a.m., the exact time the gunman shot Giffords and methodically mowed down a line of people waiting to talk to her during a congressional meet-and-greet outside a Tucson supermarket on Jan. 8, 2011.

Girl, 9, among victims remembered

About 30 others rang hand-held bells, hugged each other and cried as the time of the shooting passed. Many bowed their heads in prayer.

Giffords and her husband, former astronaut Mark Kelly, went to the scene of the shooting Saturday. They also visited University Medical Center, where Giffords was treated after the attack, and a trailhead outside Tucson named in honour of Zimmerman.

Serenity Hammrich, right, and Jamie Stone, best friends of nine-year-old shooting victim Christina-Taylor Green, speak during a memorial ceremony on the one-year anniversary of last year's shooting rampage in Arizona. (Ross D. Franklin/Associated Press)

The couple was to join thousands at an evening candlelight vigil at the University of Arizona, with Kelly expected to speak. At an afternoon event at the University of Arizona, Colorado Senator Mark Udall, who was born and raised in Tucson, spoke about Giffords.

Of nine-year-old Christina-Taylor Green, her two best friends recalled a girl who aspired to dance with Beyonce, to be the first woman in Major League Baseball and one day be elected president United States.

"She wasn't afraid of boys or sports or anything," Serenity Hammrich said, wearing a black dress and standing with Jamie Stone on stage while many in the audience wept. "When she made student council, I was so happy for her. She believed it was important to help others to try to make a difference in the school and to put others first."

The Rev. Andrew Ross, spoke for shooting victim and his congregant Phyllis Schneck.

Congresswoman Gabrielle Giffords, seen in a March 2010 photo. (Associated Press)

"I remember just shaking and as I shared with my congregation, my immediate response was anger, in fact rage, that someone would once again do this to a member of our flock," Ross said. "And so it's good for us to be honest and admit it's not easy remembering this day. We have to be honest about that."

Jared Lee Loughner has pleaded not guilty to 49 charges in the shooting. The 23-year-old, who has been diagnosed with bipolar disorder, is being forcibly medicated at a Missouri prison facility in an effort to make him mentally ready for trial.

President Barack Obama called Giffords on Sunday to offer his support and tell her he and his wife are keeping her, the families of those killed and the whole Tucson community in their thoughts and prayers, according to the White House. He said Giffords was an inspiration to all Americans.