PORTLAND, Ore. – The gunman who killed two people and himself in a shooting rampage at an Oregon mall was 22 years old and used a stolen rifle from someone he knew, authorities said Wednesday.

Jacob Tyler Roberts had armed himself with an AR-15 semiautomatic rifle and had several fully loaded magazines when he arrived at a Portland mall on Tuesday, said Clackamas County Sheriff Craig Roberts.

The sheriff said the rifle jammed during the 22-year-old’s attack, but he managed to get it working again. He later shot himself.