TUCSON, Ariz. (The Blaze/AP) -- The "shady individual" showed up at a public gathering for Rep. Gabrielle Giffords asking to see the lawmaker, according to event volunteer Alex Villec. Told he would have to wait his turn, the man left but returned minutes later and gunfire erupted.
The man, wearing a black cap and baggy pants and shirt, rushed by a table separating him and Giffords, raised an arm, and then came shots, Villec, 19, told The Associated Press.
Firing a semiautomatic weapon, the gunman targeted Giffords as she met with constituents around 10 a.m. Saturday outside a busy Tucson supermarket. Authorities said Arizona's chief federal judge and five others were killed and 13 people were wounded, including the Democrat lawmaker.
He also fired at her district director and shot indiscriminately at staffers and others standing in line to talk to the congresswoman, said Mark Kimble, a communications staffer for Giffords.
"He was not more than three or four feet from the congresswoman and the district director," Kimble said, describing the scene as "just complete chaos, people screaming, crying."
Pima County Sheriff Clarence Dupnik said the rampage ended only after two people tackled the gunman.
"He was definitely on a mission," said Villec, a former Giffords intern.
Police say the shooter was in custody, and was identified by people familiar with the investigation as Jared Loughner, 22. U.S. officials who provided his name to the AP spoke on condition of anonymity because they were not authorized to release it publicly.
His motivation was not immediately known, but Dupnik described him as mentally unstable and possibly acting with an accomplice. His office said a man possibly associated with the suspect who was near the scene was being sought. The man, who was photographed by a security camera, was described as white with dark hair and 40-45 years old:
The assassination attempt left the three-term congresswoman in critical condition after a bullet passed through her head.
The accused killer is 22-year-old Justin Loughner. He's suspected of killing six people and wounding Arizona Rep. Gabrielle Giffords, and was decribed as a disturbed young man who was rejected by the military and frequently disrupted his college class.
The Tucson neighbors of the 22-year-old Loughner said he often kept to himself - not hostile to anyone but certainly not warming up to anyone, either.
"He was a guy in high school who definitely had his opinions on stuff and didn't seem to care what people thought of him," said Grant Wiens, 22, who told The Associated Press he went to high school and had a class at Pima Community College with Loughner.
Loughner was in custody after authorities said he opened fire outside a grocery store as Giffords, a Democrat, met with voters. The rampage killed six people including Arizona's chief federal judge. Giffords was among 13 people wounded.
Authorities said the accused gunman targeted the three-term congresswoman, but an exact motivation was not immediately known. Many questioned whether the nation's polarized political climate had played a role, even as Loughner's political views remained unclear late Saturday.
Pima County Sheriff Clarence Dupnik described the gunman as mentally unstable and said he possibly acted with an accomplice.
Lynda Sorenson said she took a math class with Loughner last summer at Pima Community College's Northwest campus and told the Arizona Daily Star he was "obviously very disturbed."
"He disrupted class frequently with nonsensical outbursts," she said.
In a Dec. 15 YouTube video, Loughner describes himself as a U.S. military recruit.
Federal law enforcement officials poured over versions of a MySpace page that belonged to Loughner and over a YouTube video published weeks ago under an account "Classitup10" and linked to him. The MySpace page, which was removed within minutes of the gunman being identified by officials, included a mysterious "Goodbye friends" message published hours before the shooting and exhorted his friends to "Please don't be mad at me."
On his MySpace page, Loughner spoke of how he liked to read and he also wrote repeatedly about literacy, complaining that the rate was especially low in the congressional district where he lived.
"The majority of people, who reside in District-8 are illiterate hilarious. I don't control your English grammar structure, but you control your English grammar structure," he said.
In an interview with The Associated Press, Wiens also said Loughner used to speak critically about religion. He also talked about how he liked to smoke pot.
"He wasn't really too keen on religion it seemed like," Grant Wiens, 22, told The Associated Press. "I don't know if floating through life is the right term or whatever, but he was really just into doing his own thing."
Loughner's MySpace profile indicated he attended and graduated from school in northwest Tucson and had taken college classes. He did not say if he was employed.
Tamara Crawley, director of the Marana Unified School District in Tucson, said Loughner attended Mountain View High School in Tucson for three years but withdrew after completing his junior year in 2006. Crawley did not know why Loughner had withdrawn from Mountain View High and it was not clear if he had transferred to another school in the area.
The Army released a statement indicating Loughner was not accepted.
In October 2007, Loughner was cited in Pima County for possession of drug paraphernalia, which was dismissed after he completed a diversion program, according to online records.
A year later he was charged with an unknown "local charge" in Marana near Tucson. That charge was also dismissed following the completion of a diversion program in March 2009, the Daily Star reported.
Ryan Miller, 19, was a sophomore at Mountain View when Loughner was a senior. He said Loughner was seemed like a normal kid.
"I was in shock," he said, describing his reaction to the shooting. "I didn't know what possessed someone our age to do something like this."
The Associated Press Contributed to this report.