WASHINGTON (AP) – President Barack Obama plans to travel on Wednesday to Tucson, Arizona, to help a rattled nation deal with the deadly outburst of violence that left six people dead and a U.S. congresswoman gravely wounded.

Late Monday, White House spokesman Nick Shapiro said Obama would speak at a memorial service for the victims of the shooting rampage. He said first lady Michelle Obama would also attend the service at the University of Arizona.

It was many hours earlier, on a frigid winter’s morning in Washington, that Obama led a national moment of silence for the 20 people shot outside a grocery store in Arizona on Saturday, including Democratic Rep. Gabrielle Giffords. She was the target of the attack and, remarkably, was fighting for recovery despite being shot in the head from close range. Six other people were killed, including a nine-year-old girl, a federal judge and an aide to the congresswoman.

With the House and Senate in recess, the Capitol was relatively quiet, with only the occasional tour group in the Rotunda or the old Senate chamber. In a nearby office building, people lined up to signs books of condolences and best wishes. Security felt tighter.

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“In the coming days, we’re going to have a lot of time to reflect,” the president said from the Oval Office. “Right now, the main thing we’re doing is to offer our thoughts and prayers to those who have been impacted, making sure that we’re joining together.”

Obama and congressional leaders were figuring out their next steps in response to the shooting, searching for the right time, place and tone for a unifying moment. The president said the whole country needs to show its loss but also speak to a sense of hope. The question, he said, is “how, out of this tragedy, we can come together as a stronger nation.”

Congress scuttled its schedule. Sadness, anger and disbelief took over.

“I traveled to Iraq with Gabby several years ago. We walked the streets of Baghdad together and did not face the violence she faced over the weekend in her own country,” said Democratic Rep. C.A. Dutch Ruppersberger, referring to Giffords by her nickname.

Rather than the overtly political plan of voting on the repeal of Obama’s signature health care overhaul, the House will vote this week on a resolution of support for Giffords and the other victims of the shootings.

Giffords’ doctors said they were optimistic for her survival and recovery, though just determining the extent of such brain injuries can require weeks or months.

In the Senate, Republican leader Mitch McConnell said the Arizona shootings won’t deter members from doing their jobs. “A strong democracy depends on a free and robust exchange of ideas,” he said. “The actions of one deranged man this past weekend will not hinder that.”

Prosecutors have charged 22-year-old Jared Loughner with the shootings.

At the Capitol, the chief law enforcement official in the House, Sergeant-at-Arms Bill Livingood, and representatives from the Capitol police briefed congressional staff on the shooting. He counseled them on steps they should take to ensure the safety of lawmakers and their constituents.

He said congressional offices should establish a contact with local law enforcement, When lawmakers are home, he said, they should share their schedule with local police. He also pleaded with staff members to fill out an emergency contact form.

Amid the mourning, Democratic Sen. Frank Lautenberg of New Jersey, a longtime advocate of gun control, said he would introduce legislation later this month to ban high-capacity ammunition clips. The measure would re-establish a prohibition that lapsed in 2004 on clips that feed more than 10 rounds at a time. The Glock pistol used in Saturday’s attack had such a high-capacity ammunition magazine.

“The only reason to have 33 bullets loaded in a handgun is to kill a lot of people very quickly. These high-capacity clips simply should not be on the market,” Lautenberg said in a statement.

As Washington’s agenda adjusted, Obama postponed an economic trip to New York on Tuesday. Michelle Obama, scrapped her own Tuesday event with business leaders until a more appropriate time.

At 11 a.m. EST Obama and his wife walked out of the White House to the sounding of a bell. They stood in silence, flanked by the collection of advisers, kitchen staff, maintenance workers and clerks who keep the White House running.

The scene was reminiscent of the moment of silence held every year on Sept. 11.

At the same time, farther down Pennsylvania Avenue, hundreds of legislative aides stood on the east steps of the Capitol, heads down in silence. And at the Supreme Court, the justices paused to reflect, too, between the two cases they were hearing Monday morning.

The White House said Obama had called Gifford’s husband, astronaut Mark Kelly, and the family of Christina Taylor Green, a 9-year-old girl killed in Saturday’s attack, among others.

Obama also sought to shift some attention to those who acted with bravery as a horrifying scene unfolded in front of them on Saturday in Tucson. He spoke of a college student who ran into danger to rescue his boss, and a woman who helped keep the suspect from reloading ammunition, and other citizens who wrestled the man to the ground.

“Part of what I think that speaks to,” Obama said, “is the best of America.”

Associated Press writers Ben Feller, Laurie Kellman, Donna Cassata, Julie Pace, Erica Werner, David Espo and Kevin Freking contributed to this report.

Copyright 2011 The Associated Press.