Pima County Sheriff's officials said the gunman used a pistol to carry out the rampage. The suspect has been taken into custody.

People familiar with the investigation identified the gunman as Jared Loughner, 22.

Handout photo of Jared Loughner, suspected in the shooting of a federal judge, congresswoman and others in Arizona on Saturday. [Xinhua/Reuters Photo]

In the messages posted on MySpace and YouTube web pages before the rampage, Loughner talked about his distrust of the government and suggested that anyone can call anyone a terrorist.

"I can't trust the current government because of fabrications," Loughner wrote in the YouTube message. "The government is implying mind control and brainwash on the people by controlling grammar."

He also mentioned his concern over literacy rates and the fact that nobody speaks English.

"The majority of people who reside in District 8 are illiterate - hilarious," Loughner wrote in another YouTube slide. "I don't control your English grammar structure."

District 8, an area served by Giffords, includes a 114-mile (182- kilometer) stretch of the U.S. border with Mexico.

"Goodbye," Loughner said in a message posted on his MySpace account at approximately 5 a.m. Saturday. "Dear friends ... Please don't be mad at me."

The FBI reportedly has taken over the investigation.

Giffords, a moderate Democrat, serves the 8th Congressional District, which includes a 114-mile stretch of the U.S. border with Mexico. She was re-elected to her third term last November.

During last year's campaign, Giffords touted her efforts to push the Obama administration to deploy National Guard troops to the border, and for playing an instrumental role in securing 600 million dollars in funding to add more technology and Border Patrol agents.

Giffords opposed SB 1070, Arizona's new controversial immigration law, calling it "divisive," and supported instead a comprehensive immigration reform at the national level, according to The Arizona Republic, a local newspaper.

Giffords was a member of the Arizona House and Senate before going to Washington.