* Surviving victim, a teenage girl, remains in serious condition
* Police to release victim's and shooter's names on Wednesday
* Hockey mask and rifle recovered from scene
Dec 12 (Reuters) - A teenage girl wounded in a shooting spree at an Oregon shopping mall that left three dead, including the suspected gunman, is in serious condition, a hospital official said on Wednesday.
Kristina Shevchenko was one of at least three people shot when a man wearing what appeared to be a hockey mask opened fire with a rifle at the crowded Clackamas Town Center in the Portland suburb of Happy Valley.
Police will release the names of the victims and the shooter at a news press conference at 10 a.m. PST (1800 GMT) on Wednesday, Clackamas County Undersheriff Matt Ellington said on CNN. Shevchenko's name was released by the Oregon Health & Science University Hospital on authorization of her family.
"The family is doing OK," Shevchenko's brother, Yevgeniy, said. He said his sister was 15 years old and declined further comment.
In a Facebook posting Tuesday night, Yevgeniy Shevchenko said: "As of now she is stable and sleeping. the bullet went trough bruising her lung, it missed any vital organs and it missed her ribs. she will need 2 more operations. we appreciate any and all support including your prayers! thank you."
Ellington said on CNN that police have recovered a rifle, multiple shell casings and a mask matching the one witnesses said was worn by the shooter.
He said authorities have no idea of the motive of the gunman, who died of a self-inflicted gunshot wound and appears to have had no connection to the victims.
The afternoon rampage touched off panic inside the mall, sending thousands of shoppers streaming out as police and fire crews arrived.
The incident marked the latest in a string of shooting rampages this year that included the killing of 12 people and wounding of 58 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 1.4 million- square-foot mall.
"Shooting in the middle of clackamas town center. 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 (3 meters) away from us, wearing a white mask and carrying something heavy with both hands," Baggs said in a report on the newspaper's website. "He went running into the store."
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, aired on CNN, showed shoppers heading toward exits with their arms raised above their heads.
Ellington said the Clackamas Town Center mall had been used recently by police for a mass evacuation drill. (Reporting by Chris Francescani in New York; Writing by Dan Burns and Dan Whitcomb; Editing by Bill Trott)