Representative Gabrielle Giffords was holding a Saturday morning meet-and-greet at the Safeway store off a busy suburban thoroughfare in the desert city of Tucson when a gunman sprayed the crowd with bullets.
"It was like a string of fireworks," said Tony Martinez, 31, a restaurant worker who had stopped at Safeway to pick up cheese and immediately raced out to his car.
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"It happened so fast. Then it was silent but it was still chaos as there were bodies everywhere. They covered the congresswoman's body with a tablecloth," he said.
Giffords was rushed to a hospital in Tucson, a city of rolling desert and omnipresent cactus and agave plants an hour north of the Mexican border. Officials said Giffords was critically injured but would hopefully recover.
The apparent assassination bid was denounced across the US political spectrum as reports emerged that alleged gunman Jared Lee Loughner, 22, had posted incoherent messages on the Internet.
Growing vitriol of politics in Arizona
But for some residents, the violence was also a sign of the growing vitriol of politics in Arizona which came under the national spotlight last year after it approved sweeping rules against illegal immigration.
"This is just terrible. They listen to these idiots on TV and on the blogs. She's a nice lady, married to an astronaut," said Frank Worth, the manager at a steakhouse near the site of the shooting.
"I say just try him, give him 30 days and then kill him. But instead he'll probably spend his life in prison and millions of dollars will go to that instead of the people who need it," Worth said.
Giffords is a member of President Barack Obama's Democratic Party but belongs to its more conservative wing. She has advocated tougher law enforcement on the border and, incidentally, the right to gun ownership.
Giffords had been a top target of the right-wing Tea Party movement but narrowly won re-election in November. Former vice presidential candidate Sarah Palin, a Tea Party favourite, had put Giffords on what she termed a "hit list," largely due to the congresswoman's support for Obama's health care reforms.
"It's hard not to feel that the derogatory tone of politics in Arizona has played a part in allowing something like this to happen," said Kate Donovan, who joined hundreds of other Tucson residents in a candlelight vigil outside of the hospital where Giffords and other victims were being treated.
"To contemplate that a person could lose their humanity and do something like this. My hope is that it won't stop people from fighting for justice," she said.
Palin offered her condolences to the dead and said she was praying for the victims and their families.
Fresh blow to state's image
Arizona Governor Jan Brewer, a Republican who has become a lightning rod for criticism for championing the state's controversial immigration law, acknowledged that the shooting would inflict a fresh blow to the state's image.
"It certainly doesn't show favor on the state of Arizona," Brewer told reporters. "But we have a lot of good, decent people here."
For many Arizona residents, the tragedy went beyond politics.
"I just can't believe that this has happened, that someone can have so much malice in him," said Judy Roads, who joined the mourners outside of the hospital.
"It's too early to know what motivated him, but really, it's irrelevant," she said.
