The Tuesday afternoon shooting rampage at the crowded Clackamas Town Centre in the Portland suburb of Happy Valley touched off panic inside the mall, with shoppers streaming out as police and fire crews arrived on the scene.
"I can confirm that we believe at this point that there was one and only one shooter involved and that that shooter is deceased," Clackamas County Sheriff's spokesperson Lieutenant James Rhodes told a press briefing.
"In addition to that, we have at least one patient who was taken from the mall with a traumatic injury and at least two that were deceased in addition to the shooter," he added.
Rhodes said later that the suspect died from a self-inflicted gunshot wound and that police had not fired a single shot inside the mall. The wounded victim was taken by helicopter to a hospital where a spokesperson said she was in serious condition.
The incident marked the latest in a string of shooting rampages this year that included the killing of 12 people and wounding of 58others at a midnight screening of The Dark Knight Rises in Colorado.
In Oregon, police evacuated terrified shoppers, who were reported by local media and via Twitter to have hidden in the back rooms of shops as gunshots rang out in the mall.
"Shooting in the middle of Clackamas Town Centre. I'm stuck in the back room of build a bear!" one person tweeted.
High school student Hannah Baggs (14) told the Oregonian newspaper that she got a close look at the gunman before he entered the mall and opened fire.
"He was, like, 10 feet away from us, wearing a white mask and carrying something heavy with both hands," Baggs said in remarks carried on the newspaper's website. "He went running into the store."
Man in Santa suit 'hit the floor'
The Oregonian also said on its website that the gunman had used a semi-automatic rifle and may have also been wearing body armour, but police did not immediately confirm that. The paper said the shooting occurred near the mall's food court.
"All of a sudden I heard something similar to a .22 popping, probably eight times, and people dropping everywhere, people screaming," witness Christina Fisher said in an interview aired on CNN. "It was chaos."
A man dressed in a red Santa suit and beard who said he greets children at the mall told local KGW-TV that he heard some 15 gunshots and realised that there was a gunman on the loose.
"So I hit the floor," the man told KGW-TV in an interview outside the mall. "My crew that was working with me must have left and everybody that was in the [Christmas] set must have left, because when I got up there was nobody in the set but myself."
Police and Swat teams established a perimeter around the scene and worked to evacuate the mall as they searched for the gunman. Video footage from inside the mall, which aired on CNN, showed shoppers heading toward exits with their arms raised above their heads.
The identities of the dead and wounded were not immediately released. A mall spokesperson directed calls to law enforcement authorities.
"My thoughts and prayers are with the victims and their families," Oregon Governor John Kitzhaber said in a statement released by his office. "I appreciate the work of the first responders and their quick reaction to this tragic shooting." – Reuters