A 20-year-old man has been charged with five counts of first-degree murder after confessing to a shooting rampage at a mall in Burlington, Washington over the weekend, prosecutors say in court papers.
Turkish-born Arcan Cetin, a legal US resident, was advised of the charges against him during a brief hearing in Skagit County District Court in Mount Vernon, Washington on Monday morning and ordered held on US$2 million (NZ$2.7 million) bail.
Skagit County District Attorney Richard Weyrich declined to discuss a motive for the shooting rampage.
The FBI has said there was no indication the attack was an act of terrorism, but has not ruled out that possibility.
Wearing red and blue jail garb and shackled at the waist, Cetin showed no emotion and spoke only to respond "yes, your honour" several times to the judge.
According to charging documents, while being questioned by police investigators Cetin admitted bringing a Ruger .22 caliber rifle into the Macy's department store at Cascade Mall in Burlington on Friday evening and fatally shooting five people.
Prosecutors have yet to decide whether to seek the death penalty in the case.
The attack follows a series of violent outbursts at shopping centres across the United States, including the stabbing of nine people at one in Minnesota on Septemver 17. The Federal Bureau of Investigation has said it considers that attack a "potential act of terrorism".
According to the charging documents, Cetin initially walked into the mall unarmed, through a Chuck E. Cheese family entertainment and pizza restaurant, then went back to his car to retrieve the rifle from his trunk, moving the car closer to Macy's.
Cetin walked into the Macy's shortly after, gunning down a 16-year-old girl near a rack of clothing and then opening fire on the other four victims in the make-up department before placing the gun on a cosmetics counter and walking out, prosecutors say in the court papers.