Tucson, Arizona (CNN) -- It was a day and an event like so many others -- until it wasn't.
Six people were killed and 12 others wounded, including U.S. Rep. Gabrielle Giffords, when a gunman opened fire in front of a Safeway supermarket in Tucson, Arizona, authorities said. The congresswoman had been hosting a meeting with constituents Saturday morning when the attack began.
Dr. Steven Rayle told CNN's Wolf Blitzer he was about 10 feet away from Giffords when the gunman shot the congresswoman.
"He continued to fire, sort of rapidly, really at point-blank range. And the way things were set up, people really had no route to escape. They were sort of hemmed in by the architecture and the things around there," he said.
After a moment of hesitation, Rayle said he ducked behind a concrete post, then laid on the ground so as not to be a target.
Rayle said the suspect "had a sort of determined look on his face" as he opened fire.
"He was not sort of going around and picking out people and firing at them ... He was just firing his gun indiscriminately," he said.
The 22-year-old suspect, who law enforcement sources identified as Jared Lee Loughner, was trying to reload when he was tackled to the ground, another witness said.
The gun, which another bystander had wrestled from the gunman, was empty and cocked open. The shooter had another magazine at the ready, Joe Zamudio told CNN.
"He was ready for war. He was not playing around," Zamudio said. "He was going to keep shooting. It was not over. He had just ran out of bullets."
Zamudio said he was one of the bystanders who pinned the gunman to the ground until police showed up.
Jason Pekau, who works at a nearby store, said he heard the gunshots from 50 yards away.
"It sounded like tons of pots and pans falling down on the ground right next to my ear it was so loud," he said.
He described a chaotic scene in the parking lot immediately after the attack.
"I just saw people running, screaming towards where the shooting happened. Everyone screaming that it was Gabrielle Giffords," he said.
Witnesses told him she was shot "point-blank in the head," Farley said.
"I did see them take her away on a stretcher," Pekau said about the congresswoman. "She was moving, from what I saw with my own eyes."
Giffords may owe her survival to a quick-thinking intern, an Arizona state legislator told CNN.
Arizona state Rep. Steve Farley said Daniel Hernandez, his former campaign manager -- and a trained nurse -- was interning for Giffords and staffing Saturday's meet-and-greet event.
"He said that when he was in the back ... he heard shots in the front. He rushed to see what had happened. Gabby was on the floor," Farley said. "He was able to use his nurse training and snapped right into it and was able to apply pressure to the wound and keep her active and alert. He rode with her in the ambulance to the hospital."
Video from the scene showed one of Giffords' banners still hanging in the storefront. Yellow tape was draped around the parking lot as police began their investigation.
Giffords won her third term in a closely contested race against a Tea Party-sponsored candidate and was one of three Democratic legislators who reported vandalism at their offices following the March vote on health care reform.
President Barack Obama spoke from Washington soon after the attack. He called it a national tragedy and underlined how simply the day began -- like any other.
"It's not surprising that today, Gabby was doing what she was always does -- listening to the hopes and concerns of her neighbors," said Obama, referring to the congresswoman by her nickname. "That is the essence of what our democracy is all about."