BREAKING

TUCSON, Ariz. – Rep. Gabrielle Giffords of Arizona was shot in the head Saturday and an unknown number of others were wounded when an assailant opened fire in an area where the lawmaker was meeting with constituents, officials said.

There were varying accounts on Giffords' condition, but a hospital spokesman said the Democrat was in critical condition. An aide to the Democrat was killed. An unknown number of others was injured, officials officials said, including additional aides to the lawmaker.

Congressional officials said one of the victims died soon after the attack, and others were taken to a nearby hospital. The officials said the wounded included some of Gifford's aides who were with her at the time.

One official added the attack was carried out with an automatic weapon. The officials who described the events did so on condition of anonymity, saying they were not permitted to comment publicly.

"I am horrified by the senseless attack on Congresswoman Gabrielle Giffords and members of her staff," newly elected House Speaker John Boehner said. "An attack on one who serves is an attack on all who serve. Acts and threats of violence against public officials have no place in our society. Our prayers are with Congresswoman Giffords, her staff, all who were injured, and their families. This is a sad day for our country."

They said the FBI and local law enforcement were investigating the attack, which took place while Giffords was greeting constituents outside a grocery store.

Giffords, 40, was re-elected to her third term last November. She was a member of the Arizona House and Senate before coming to Washington.

Giffords was elected to Congress amid a wave of Democratic victories in the 2006 election. The former state lawmaker won a narrow victory against a tea party favorite in the 2010 election.

The shooting comes amid a highly charged political environment that has seen several dangerous threats against lawmakers but nothing that reached the point of actual violence.

A San Francisco man upset with House Speaker Nancy Pelosi's support of health care reform pleaded guilty to threatening the Democratic congresswoman and her family, calling her directly on March 25 and threatening to destroy her Northern California home if she voted for health care reform.

In July, a California man known for his anger over left-leaning politics engaged in a shootout with highway patrol officers after planning an attack on the ACLU and another nonprofit group. The man said he wanted to "start a revolution" by killing people at the ACLU and the Tides Foundation.

Giffords herself has drawn the ire of the right, especially for her support of the health care bill.

Her Tucson office was vandlized a few hours after the House vote to approve the health care law in March, with someone either kicking or shooting out a glass door and window.