US President Barack Obama called for unity at a memorial service held in honour of the victims of Saturday’s deadly shooting rampage Arizona.

Some 14,000 people gathered at the University of Arizona’s basketball arena for the service held yesterday to remember the six people killed and 13 injured in the attack at a supermarket in Tucson.

In a 33-minute eulogy, Mr Obama rallied the nation to aspire for a better America.

“I believe we can be better,” he said. “Those who died here, those who saved lives here – they help me believe. We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us.”

Mr Obama refrained from blaming the tragedy on polarised political rhetoric and party campaigns, as some have done, but urged Americans to talk with one another “in a way that heals, not in a way that wounds” as he expressed his regret over the “point-scoring and pettiness that drifts away with the next news cycle”.

“The forces that divide us are not as strong as those that unite us,” he said.

“Rather than pointing fingers or assigning blame, let us use this occasion to expand our moral imaginations, to listen to each other more carefully, to sharpen our instincts for empathy, and remind ourselves of all the ways our hopes and dreams are bound together.”

The crowds erupted into elated cheers when Mr Obama revealed that shortly after a hospital visit to Representative Gabrielle Giffords, the Democrat had opened her eyes for the first time since being shot in the head at point blank range during the rampage.

Giffords, known as Gabby, had been meeting members of the public at a Safeway supermarket when 22-year-old Jared Loughner opened fire. She remains in intensive care and has responded to simple commands such as moving her fingers, but doctors remain uncertain about the extent of the recovery she will make.

Mr Obama said: “Gabby opened her eyes, and I can tell you she knows we are here, she knows we love her, and she knows we are rooting for her.”

He went on to remember each of those killed, including nine-year-old Christina Taylor Green who was interested in politics and dreamed of becoming the first female baseball player in the major leagues.

Victims also included Federal Judge John Roll who had stopped by to say hello to Giffords on his way back from Mass.

In Washington, Democrats and Republicans put aside their political differences as they paid tribute to Giffords and the victims on Wednesday.

House Speaker John Boehner led a bipartisan prayer service in which he vowed not to allow the assassination attempt hinder democracy.

“No assailant’s bullet, no twisted act of violence or cruelty, can silence the sacred dialogue of democracy,” he said.