Jacob Tyler Roberts, 22, identified as police as the suspect in Tuesday's shooting at the Clackamas Town Center shopping mall, is seen in this undated picture released by the Clackamas County Sheriff's Office December 12, 2012. Roberts opened fire Tuesday in a crowded Oregon shopping mall, killing two people and wounding a third before taking his own life and appeared to have acted in a blind rampage with no known motive, authorities said on Wednesday. REUTERS/Clackamas County Sheriff's Office/Handout (UNITED STATES - Tags: CRIME LAW) THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS
CLACKAMAS, Ore., -- A masked gunman who opened fire in the food court of a crowded Oregon shopping mall, killing two people and wounding a third before taking his own life, appears to have acted alone in a blind rampage with no known motive, police said on Wednesday.
Investigators identified the man behind Tuesday afternoon's shooting as Jacob Tyler Roberts, 22, who they said had no significant criminal history and apparently acted without warning.
The weapon he used was described as an AR-15 semiautomatic rifle, which the Clackamas County Sheriff's Office said was stolen the day before the shooting from an unidentified acquaintance of the killer.
Roberts also was believed to be carrying several fully loaded ammunition magazines when he walked into the Clackamas Town Center in the Portland suburb of Happy Valley, and moved swiftly to a food court at the center of the mall to start shooting, authorities said. He was wearing a hockey-style mask at the time.
Two people were killed on the spot -- Steven Mathew Forsyth, 45, of suburban West Linn, a father of two who owned a business in the mall, and Cindy Ann Yuille, 54, of Portland, according to Sheriff Craig Roberts.
Kristina Shevchenko, 15, was badly wounded but managed to stagger away from the food court to the lower level of the mall, where she was found. She was hospitalized in serious condition on Wednesday.
But carnage from the shooting likely was limited by the fact that the gun jammed, although the suspect managed to get the weapon working again before he moved downstairs and shot himself, the sheriff told a news conference.
Sheriff Roberts also said the casualty count was curtailed by the fact that the estimated 10,000 shoppers in the mall "kept a level head" for the most part in swiftly leaving the building, and helping each other in the process.
He credited police with rapidly swarming the mall and merchants with following emergency lockdown procedures that allowed many shoppers to quickly find shelter.
Authorities said they remained baffled about what led the suspect to open fire in the mall, the latest in a spate of U.S. gun violence incidents this year, most notably the killing of 12 people and wounding of 58 others at a midnight screening of the Batman film "The Dark Knight Rises" in Colorado in July.
"At this time, we do not understand the motive of this attack except to say there is no apparent connection between the suspect and his victims," the sheriff said.