Talking to reporters Wednesday, Clackamas County Sheriff Craig Roberts said 22-year-old Jacob Tyler Roberts was wearing a hockey-style face mask and using a stolen gun when he opened fire in an Oregon shopping mall near Portland.
The gunman drove to Clackamas Town Center and entered the crowded mall through a rear entrance at Macy's, the sheriff said.
"We believe he was carrying several fully loaded magazines," Roberts said. "This was a heartbreaking tragedy by any standard."
Authorities also identified the shooting's victims and displayed a timeline of what happened.