Shocking attack: US Representative Gabrielle Giffords of Arizona was shot in the head outside a grocery store in Tucson while holding a public event, National Public Radio reported on Saturday.

A hospital spokeswoman said the congresswoman was in critical condition. According to reports, six people were killed and at least 12 people were injured in the incident.

The shooter was identified as Jared Loughner.

More than 15 people were reportedly shot when an unidentified gunman ran up and began shooting indiscriminately as Giffords addressed supporters.

One official added the attack was carried out with an automatic weapon.

Giffords was shot point blank in the head, Fox said. She was airlifted to a hospital following the shooting attack.

The New York Times quoted Dr. Steven Rayle, a former emergency room doctor, who said he witnessed the attack. According to his account, Giffords was standing behind a table outside a Safeway and greated passersby when the assailant approached her from behind and fired at her head from point-blank range.

“He must have got off 20 rounds,” Rayle was quoted as saying.

The gunman was wrestled to the ground and taken into custody, Fox said, citing an eyewitness.

Some other members of the Democratic Party, possibly GIffords' aides, were among those hurt in the attack. Federal judge John Roll was also reportedly among those killed in the shooting. Doctors later said that a 9-year-old girl was among the fatalities.

'Your best bet is a Jewish woman'

President Barack Obama called the incident an "unspeakable tragedy" and confirmed that several people died in the attack.

"This morning, in an unspeakable tragedy, a number of Americans were shot in Tucson, Arizona, at a constituent meeting with Congresswoman Gabrielle Giffords. And while we are continuing to receive information, we know that some have passed away, and that Representative Giffords is gravely wounded.

"We do not yet have all the answers. What we do know is that such a senseless and terrible act of violence has no place in a free society. I ask all Americans to join me and Michelle in keeping Representative Giffords, the victims of this tragedy, and their families in our prayers," the president said.

Giffords, 40, a Democrat, is married to US astronaut Mark Kelly. She took office in January 2007, emphasizing issues such as immigration reform, embryonic stem-cell research, alternative energy sources and a higher minimum wage. She is the first Jewish woman from Arizona to be elected to Congress and is also known as a pro-choice supporter but also as a supporter of gun rights.

Giffords highlighted her Jewish identity as part of her first Congress campaign.

“If you want something done, your best bet is to ask a Jewish woman to do it,” she said at the time.

Strong connection to Israel

Giffords is the granddaughter of Akiba Hornstein, the son of a Lithuanian rabbi who in the 1940s moved from New York to Tucson. He later changed his name to Giff Giffords in an effort to avoid anti-Semitism.

Gabrielle Giffords first visited Israel in 2001 as an Arizona senator, later saying that she felt very committed to Judaism and that the visit provided her with a basis to better understand who she is and where she came from.

Upon returning to Arizona, she introduced legislation that helped Holocaust survivors.

Giffords was in Israel again last month and also visited a synagogue. She was planning to return to Israel in the summer.

In a recent visit at the Temple Emanuel synagogue she told the congregation that the US must remain committed to Israel, the Middle East's only democracy. Last week, she wrote in Arizona's Jewish newspaper that there would be no peace in the region before the Palestinian leadership and other organizations accept Israel's right to exist.

Yitzhak Benhorin, Roi Simyoni and Associated Press contributed to the report