Doctors upgrade Gabrielle Giffords' condition to serious

"The Congresswoman continues to do well," the University Medical Center in Tucson, Arizona, said in a statement.

Giffords was the target of a mass shooting by 22-year-old Jared Lee Loughner that killed six and wounded another 13 on January 8. On Sunday reports said she started breathing on her own.

Giffords, 40, was shot in the head as she was addressing her supporters in Tucson. She underwent brain surgery, and doctors said they were "cautiously optimistic" about her recovery.

Giffords is known as a moderate centrist politician and a rising star among American lawmakers. A third-term Democrat in the U.S. House of Representatives, she supported the right of Americans to bear arms and criticized existing immigration laws, Kazinform cites RIA Novosti /www.en.rian.ru /

U.S. President Barack Obama called the shooting a "senseless and terrible act of violence" and an "unspeakable tragedy."

Loughner could face the death penalty if found guilty.