Rep. Gabrielle Giffords (D-Ariz.) underwent a tracheotomy Saturday to replace the breathing tube that ran down her throat with a different tube in her windpipe, thus freeing her from a ventilator, the University Medical Center in Tucson said on its website.

Giffords "remains in critical condition" but "her recovery continues as planned."

"Surgeons also inserted a feeding tube (percutaneous endoscopic gastrostomy [PEG]) to provide nutritional support," the university said. "These procedures are not uncommon among brain-injured patients in the Intensive Care Unit."

One other victim of last weekend's shooting that left six people dead and injured 13 others was discharged Saturday, and two others remain in good condition. A media briefing to provide a "full update" on patients' conditions has been scheduled for Monday, the university added.

Also Saturday, the Safeway supermarket where Giffords and 18 others were shot one week ago reopened. Local residents told the Associated Press that business was brisk and that the reopening was another sign that the community is healing and slowly getting back to normal.

At 10 a.m. local time - noon in the nation's capital - the store asked customers to step outside for a moment of silence exactly one week after the shooting.

"Our employees have been through so much but they are here, they're working and kind of anxious to reconnect with their customers and the community. We're doing OK," store spokeswoman Cathy Kloos told the Associated Press.