US congresswoman Gabrielle Giffords is in a critical condition after being shot in the head while a nine-year-old girl and at least two others have been killed after an assailant opened fire as the Democrat was meeting constituents in Arizona, congressional officials said.
The officials said one of the victims, an aide to Ms Giffords, died soon after the attack and others injured in the attack were taken to a nearby hospital. A US Marshal confirmed that district Judge John Roll also died.
One official added the attack was carried out with an automatic weapon. US Capitol police say the gunman, who has been identified as Jared Laughner, is in custody.
The FBI and local law enforcement officials are investigating the attack, which took place while Ms Giffords was greeting constituents outside a shop in Tucson.