Arizona shootings: US mourns dead after Giffords attack
The US is mourning the deaths of six people in a shooting in Arizona on Saturday which left a congresswoman seriously wounded.
Flags across the US have flown at half mast, and President Barack Obama says the nation is "grieving and shocked".
The man charged with the attack, Jared Loughner, is to appear in court later.
Representative Gabrielle Giffords, who was shot in the head, remains in a critical condition but doctors say the swelling in her brain has stabilised.
She had been holding an open-invitation meeting with constituents outside a supermarket in Tucson when a man holding a gun approached and opened fire.
Ms Giffords, 40, was shot from close range by the gunman, who then began shooting into the crowd.
Among the dead were a nine-year-old girl and a federal judge. A total of 14 people were injured, in addition to the six who were killed.
The girl, Christina Taylor Green, was born on 9/11 and featured in a book Faces of Hope, Babies Born on 9/11 about some of the children born on that day.
President Obama praised the "extraordinary courage" of the people at the scene who wrestled the gunman to the ground, saying they had showed "the best of America".
One of the priorities was "making sure we are joining together, pulling together as a country," he added.
Earlier, Mr Obama led the nation in a silent tribute from the South Lawn of the White House.
About 300 White House staff members joined the brief outdoor ceremony, bowing their heads as a marine honour guardsman rang a bell three times.
On the east steps of the Capitol building, hundreds of congressional staffers also paid tribute to Ms Giffords and the other victims of Saturday's shooting.
The BBC's Jonny Dymond, in Tucson, says small groups gathered in public spaces, in offices and in shops and stopped in silence for a minute.
This city did not come to a halt, our correspondent says, as many had done their mourning over the weekend in public vigils and private houses.
The crew on board the International Space Station (ISS) also paused for a brief silence. The commander on the ISS is Ms Giffords' brother-in-law, Cmdr Scott Kelly. Her husband, Mark Kelly, is also an astronaut.
""As I look out the window, I see a very beautiful planet that seems very inviting and peaceful," said Cmdr Kelly. "Unfortunately, it is not.
"These days, we are constantly reminded of the unspeakable acts of violence and damage we can inflict upon one another, not just with our actions but also with our irresponsible words.
"We are better than this. We must do better."
The Speaker of the House of Representatives, Republican John Boehner, called on fellow legislators to "stand together" and "rally round our wounded colleague".
The House has postponed all legislative debates next week, including a controversial bill to repeal Mr Obama's healthcare reform.
The doctors treating Ms Giffords say she remains in a critical condition but scans do not show the swelling in her brain getting any worse.
She continues to respond to simple commands to move her fingers or toes, though doctors refused to specify which parts of her body she was able to move.
"At this phase in the game, no change is good and we have no change," said neurosurgeon Dr Michael Lemole.
In all, eight people remain in hospital following Saturday's attack.
Some commentators and politicians have blamed violent rhetoric and hatred conveyed in the media for the shooting.
"People think now if they want to make a statement, they can do that by bringing bodily harm to someone who doesn't agree with them," Democratic Representative Ed Pastor said on CNN.
Mr Loughner will appear in court in Phoenix at 1400 local time (2100 GMT). If convicted, he could face the death penalty.
Court documents show he has been charged with:
- Attempting to assassinate Ms Giffords
- Killing two government officials, federal judge John Roll and Gabe Zimmerman, an aide of Ms Giffords
- Attempting to kill two more government officials
State authorities are expected to bring charges against him later for attacking non-government employees.
Mr Loughner has not co-operated with investigators, instead invoking his right under the US constitution to remain silent.
Local Sheriff Clarence Dupnik said he almost certainly acted alone.
"He's a typical troubled individual who's a loner," he said, quoted by AP news agency.
Investigators searching Mr Loughner's home said they had found evidence that the attack was premeditated.
They found an envelope with messages saying "I planned ahead", "my assassination", and the name Giffords.
Describing the attack, Sheriff Dupnik said a potentially worse tragedy had been averted.
A woman tackled the gunman as he tried to reload, snatching a magazine of bullets, he said.
The gunman managed to reload with another magazine, but the gun malfunctioned and two men then restrained him.
Various former classmates have described Mr Loughner as "obviously disturbed".
One of them, Lynda Sorenson, feared he might become violent.
"We do have one student in the class who was disruptive today," she wrote in an e-mail quoted by the Washington Post.
"He scares me a bit... Hopefully he will be out of class very soon, and not come back with an automatic weapon."
He was said to be a loner who had posted a number of anti-government videos and messages on social networking websites.
Shortly before the attack, he had posted: "Goodbye friends. Dear friends, don't be mad at me."