"In the coming days, we're going to have a lot of time to reflect," he said. "Right now the main thing we're doing is to offer our thoughts and prayers to those who've been impacted, making sure we're joining together and pulling together as a country."

The president called for the country to come together in prayer or reflection for those killed and those fighting to recover.

At the Supreme Court, the justices paused for a moment of silence between the two cases they were hearing Monday morning.

On a frigid morning outside the White House, Obama and first lady Michelle Obama stood side by side, each with their hands clasped, heads bowed and eyes closed. On the steps of the U.S. Capitol, congressional staff and other employees did the same.

"We're better than this," he said. "We must do better."

"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," he said.

"As I look out the window, I see a very beautiful planet that seems very inviting and peaceful," he said. "Unfortunately, it is not.

Earlier in the day, the nation observed a moment of silence for the victims, from the South Lawn of the White House and the steps of the U.S. Capitol to legislatures beyond Arizona and the planet itself. At the International Space Station, Giffords' brother-in-law, Scott, the commanding officer, spoke over the radio as flight controllers in Houston fell silent.

President Barack Obama will travel to Arizona on Wednesday to attend a memorial service for the victims.

Throngs of reporters and television news crews lined up outside the federal courthouse, where the hearing was moved from Tucson. The entire federal bench there recused itself because Roll was the chief judge.

"Yes," he said. His newly appointed lawyer, Judy Clarke, stood beside him as the judge ordered Loughner held without bail.

The judge asked if he understood that he could get life in prison -- or the death penalty -- for killing federal Judge John Roll, one of six who died in the shooting rampage at Giffords' outdoor meeting with constituents Saturday in Tucson.

Loughner seemed impassive and at one point stood at a lectern in his beige prison jumpsuit. A U.S. marshal stood guard nearby.

The three-term Democrat lay about a 100 miles away in a Tucson intensive care unit, gravely wounded after being shot through the head but able to give a thumbs-up sign that doctors found as a reason to hope.

It was the nation's first look at the 22-year-old loner accused of trying to assassinate Rep. Gabrielle Giffords.

PHOENIX—Jared Loughner, head shaved, a cut on his right temple and his hands cuffed, stared vacantly at a packed courtroom Monday and sat down. His attorney, who defended "Unabomber" Ted Kaczynski, whispered to him.

Later Monday, a moment of silence was held at the BCS national championship between Oregon and Auburn in Glendale.

In total, six died and 14 were injured or wounded outside a supermarket where Giffords set up a booth to hear the concerns of constituents. Loughner was tackled to the ground minutes after the shooting began, authorities said. He has been silent ever since.

A Mass for all the victims was scheduled Tuesday at St. Odelia's Parish in Tucson.

Among the dead was 9-year-old Christina Taylor Green, who was born on the day of the Sept. 11, 2001, terrorist attacks. Her funeral is Thursday.

It was unclear when funerals will be held for the other victims, including one of Giffords' aides.

Loughner is charged with one count of attempted assassination of a member of Congress, two counts of killing an employee of the federal government and two counts of attempting to kill a federal employee. Those are federal charges.

State prosecutors, meanwhile, are researching whether they have to wait until after the federal case is resolved, or if they can proceed with local charges at the same time, an official said.

Giffords, 40, was shot in the head at close range. She was in critical condition at Tucson's University Medical Center. Two patients were discharged Sunday night. Seven others remained hospitalized.

Recent CT scans showed no further swelling in the brain, but doctors were guarded.

"We're not out of the woods yet," her neurosurgeon Dr. Michael Lemole said. "That swelling can sometimes take three days or five days to maximize. But every day that goes by and we don't see an increase, we're slightly more optimistic."

After Saturday's operation to temporarily remove half of her skull, doctors over the past two days had Giffords removed from her sedation and then asked basic commands such as: "Show me two fingers."

"When she did that, we were having a party in there," said Dr. Peter Rhee, adding that Giffords has also managed to give doctors a thumbs-up and has been reaching for her breathing tube, even while sedated.

"That's a purposeful movement. That's a great thing. She's always grabbing for the tube," he said.

Giffords' family is by her side and is receiving constant updates from doctors. On Monday, two well-known doctors with extensive experience in traumatic brain injury were en route to Tucson to help consult on Giffords' case.

Her doctors have declined to speculate on what specific disabilities Giffords may face.

With few new details emerging at the hearing, questions remained about what could have motivated someone to arm himself with a pistol and magazines carrying 33 bullets each, and rain gunfire on a supermarket parking lot crowded with men, women and children.

And who exactly was Jared Loughner?

Comments from friends and former classmates bolstered by Loughner's own Internet postings have painted a picture of a social outcast with almost indecipherable beliefs steeped in mistrust and paranoia.

"If you call me a terrorist then the argument to call me a terrorist is Ad hominem," he wrote Dec. 15 in a wide-ranging posting.

A military official in Washington said the Army rejected Loughner in 2008 because he failed a drug test. The official spoke on condition of anonymity because privacy laws prevent the military from disclosing such information about an individual's application.

The official did not know what type of drug was detected.

Prosecutors say he scrawled on an envelope the words "my assassination" and "Giffords" sometime before he took a cab to the shopping center. Police said he bought the Glock pistol used in the attack at Sportsman's Warehouse in Tucson in November.

The revelation about the shooter's high-capacity magazines led one longtime Senate gun control advocate, Sen. Frank Lautenberg, D-N.J., to announce plans to re-establish a prohibition that lapsed in 2004 on magazines that feed more than 10 rounds at a time.

Across the country, including Nebraska and Iowa, lawmakers opening their legislative sessions observed a moment of silence. Other states flew flags at half-staff.

In Arizona, Gov. Jan Brewer said the state is grieving but united and determined.

"We are yet in the first hours of our sorrow, but we have not been brought down. We will never be brought down," she said to a standing ovation from a joint session of the Legislature, where Giffords served before being elected to Congress.

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Associated Press writers Julie Pace in Washington, Marcia Dunn in Cape Canaveral, Fla., Paul Davenport in Phoenix, and Terry Tang, Pauline Arrillaga and Alicia Chang in Tucson, Ariz., contributed to this report.

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