US authorities have charged a 22-year-old man over Saturday's Arizona shooting in which a congresswoman was seriously wounded and six people died.

美国官方已经对上周六亚利桑那州枪击案疑犯，一位22岁的男子提起诉讼，此次袭击造成一位国会女议员重伤、六人死亡。

The suspect has been described as a loner
Federal prosecutors¹ charged Jared Loughner with trying to assassinate²（暗杀，行刺） Gabrielle Giffords, 40, and killing³ two other government officials.

Mr Loughner, who is due to appear in court, could face the death penalty.

Ms Giffords is in a critical condition after being shot in the head at a public meeting in Tucson, Arizona.

She had been holding an open-invitation meeting with constituents⁴ outside a supermarket when a man holding a gun approached and opened fire.

She was shot from close range by the gunman, who then began shooting into the crowd.

Among the dead were a nine-year-old girl and a federal judge. A total of 14 people were injured, in addition to the six who were killed.

Local Sheriff Clarence Dupnik said a woman tackled（处理，抓住） the gunman as he tried to reload, snatching（抢夺） a magazine of bullets.

He managed to reload with another magazine, but the gun malfunctioned⁵（故障，失灵） and two men then restrained him.

The sheriff said they had prevented a much greater tragedy.

Police searching Mr Loughner's Tucson home said they had found an envelope with messages saying "I planned ahead", "my assassination⁶", and the name "Giffords".

So far, Mr Loughner has been charged only with offences relating to the attack on government employees, which is the responsibility of federal prosecutors.

They charged him with two counts of first-degree murder for the killings⁷ of Federal Judge John Roll and Gabe Zimmerman, an aide of Ms Giffords.

He was also charged with attempted assassination over the shooting of Ms Giffords, and two counts of attempting to murder two other aides.

The Justice Department said he would appear in court in Phoenix⁸ on Monday.

State authorities are expected to bring charges against him later for attacking non government employees.