WASHINGTON — Congresswoman Terri A. Sewell (D-Selma) has called Saturday’s shooting of Congresswoman (D-Ariz.) Gabrielle Giffords “unconscionable.”

Giffords of Arizona was shot in the head Saturday when an assailant opened fire outside a Safeway store during a meeting with constituents, killing at least six people and injuring 13 others, including the congresswoman from Arizona.

Medical authorities at the hospital said Giffords’ outlook is “optimistic.” Physicians at the University Medical Center Tuesday said Giffords, 40, remains in critical condition, but also said she is able to breathe on her own.

Dr. Michael Lemole, the chief of neurosurgery at the University Medical Center in Tucson, said in a news conference Tuesday the congresswoman is following simple commands. She is alert and responding to doctors.

Sewell said her thoughts and prayers are with Giffords, her husband, family, staff and all the victims of the attack.

“The tragedy that occurred [Saturday] is unconscionable and will not be tolerated,” Sewell said in a prepared statement. “The perpetrator that is responsible for this horrific act should be prosecuted to the fullest extent of the law.”

The suspect is identified as Jared Lee Loughner, 22. He is charged with one count of attempted assassination of a member of Congress, two counts of killing an employee of the federal government and two counts of attempting to kill a federal employee.

Investigators have said Loughner had a 30-round magazine on his Glock-19 and one round in the chamber. Of the 31 rounds, 20 struck those outside the Safeway in Tucson. Police said some victims were struck by more than one round.

Sewell said federal, state and local law enforcement authorities are investigating the shootings and “will work toward identifying ways in which to enhance security measures that affect members of Congress, our staff and constituents as we carry out our job of serving the needs of our districts.”