TUCSON, Arizona (Reuters) - A 23-year-old man pleaded guilty on Tuesday to killing six people and wounding 13 others, including then-U.S. Representative Gabrielle Giffords, in an Arizona shooting rampage last year and will be spared the death penalty in exchange.

Jared Loughner entered his guilty pleas in federal court in Tucson shortly after U.S. District Judge Larry Burns ruled that he was mentally competent to stand trial following over a year of treatment at a prison psychiatric hospital.

"I plead guilty," Loughner, dressed in a khaki prison jumpsuit with his hair trimmed short, said to each of the 19 counts read in court by Burns.

He was calm throughout the hearing and appeared to be following the proceedings closely, leaning forward slightly in his chair.

The plea deal calls for Loughner to be sentenced to seven consecutive life prison terms without the possibility of parole, sparing him the death penalty. A sentencing hearing was set for November 15.

Giffords, then a U.S. lawmaker from Arizona who was seen as a rising star in the Democratic Party, was meeting constituents at a Tucson supermarket on January 8 last year when she was shot through the head at close range.

She survived with severe injuries that left her with broken speech and a marked limp. But six other people were killed including U.S. District Judge John Roll and 9-year-old Christina-Taylor Green.

The 19 counts Loughner pleaded guilty to include murder, attempted murder and the attempted assassination of Giffords. Federal prosecutors had originally charged Loughner with 49 criminal counts and agreed to dismiss 30 of them.

During an exchange with the judge before formally entering his plea, Loughner admitted going to the "Congress On Your Corner" event hosted by Giffords armed with a loaded Glock 19 pistol and 60 additional rounds of ammunition with plans to kill the congresswoman.

He also admitted shooting other people there with the intention to kill them because they had attended the event.

U.S. Attorney General Eric Holder said that in deciding against pursuing the death penalty, he took into consideration the views of victims and their families as well as the recommendations of prosecutors.

"It is my hope that this decision will allow the Tucson community, and the nation, to continue the healing process free of what would likely be extended trial and pre-trial proceedings that would not have a certain outcome," he said in a statement.

GIFFORDS SATISFIED WITH PLEA DEAL

Mark Kelly, Giffords' husband, said in a statement before the hearing that the couple had been in touch with prosecutors and were satisfied with the plea agreement.

"The pain and loss caused by the events of January 8, 2011 are incalculable. Avoiding a trial will allow us - and we hope the whole southern Arizona community - to continue with our recovery and move forward with our lives," Kelly said.

Giffords resigned from Congress in January to focus on her recovery. Her former aide, Ron Barber, who was also wounded in the shooting spree, won a special election to fill her seat in June and will face re-election in November to serve a full two-year term.

"It is important to me that this individual will never be in the position to harm anyone ever again," Barber, who attended the court hearing, said following the plea.

Giffords did not attend the hearing.

Loughner was determined unfit to stand trial in May 2011 after he disrupted court proceedings and was dragged out of the courtroom. Court-appointed experts said he suffered from schizophrenia, disordered thinking and delusions.

He has since been held at a U.S. Bureau of Prisons psychiatric hospital in Springfield, Missouri, where he has been medicated to treat psychosis and restore his fitness to face proceedings in his prosecution.

During the mental competency portion of the hearing, prison psychiatrist Christina Pietz testified that in July, Loughner had expressed remorse for the shooting and especially for Christina-Taylor Green's death.

Susan Hileman, who was shot alongside Green after bringing the child to the event to learn about the political process, said the plea has not brought her a sense of closure.

"There's never closure because Christina is never going to ring my doorbell again," she told reporters outside the courtroom.