Tucson, Arizona (CNN) -- U.S. Rep. Gabrielle Giffords remained in critical condition early Sunday morning after a gunman shot her in the head, then opened fire on a crowd gathered at a political meet-and-greet outside an Arizona supermarket.
The Saturday morning attack left 11 others wounded and six killed -- including a federal judge and a 9-year-old girl, authorities said.
Two people tackled the suspected shooter, stopping a spray of bullets that turned a calm "Congress on Your Corner" event into what President Barack Obama later described as an "unspeakable tragedy".
Local authorities apprehended 22-year-old suspect Jared Lee Loughner at the scene, law enforcement sources said. By Saturday night, the Pima County Sheriff's Department said Loughner had been transferred to FBI custody.
Early Sunday morning, investigators released a photograph of a man between 40 and 50 years old who is "possibly associated with the suspect".
The dark-haired man was spotted at the location where the shooting occurred and was last seen wearing blue jeans and a dark blue jacket, the Pima County Sheriff's Department said in a statement.
Pima County Sheriff Clarence Dupnik told reporters Saturday that authorities were searching for a second individual who was a "person of interest" in the investigation. CNN
