Authorities on Sunday continued working to determine what prompted a 20-year-old man to open fire in a Washington state mall, killing five people.
Police arrested the suspected gunman, Arcan Cetin of Oak Harbor, Washington, on Saturday. Police said he was taken into custody without incident in Oak Harbor, some 48 kilometers southwest of Burlington where the shooting occurred on Friday night.
Cetin opened fire at the Cascade Mall around 7 pm local time on Friday in the cosmetics section of a Macy's department store, police said, killing four women as well as one man who died later at a hospital.
The mall remained closed on Saturday as investigators sifted for evidence and attempted to recreate the crime scene.
Police said what motivated Cetin's rampage remains unclear. The FBI said while they had no indication the attack was a "terrorism act," it could not be ruled out.
Police described Cetin's demeanor when apprehended as "zombie like," and said he was unarmed. Police said Cetin was born in Turkey, but described his status as that of a "legal, permanent resident" in the US.
Cetin's family, who immigrated from Turkey when Cetin was a child, was said to be cooperating with authorities.
Steve Sexton, the mayor of Burlington, described the shooting as a "senseless act."
"It was the world knocking on our doorstep and it came to our little community here," he said before acknowledging the response by law enforcement. "I know now our support goes with them to bring this son of a bitch to justice."
Authorities have not identified the victims, but local media said they ranged in age from mid-teens to mid-90s, and included a mother and her daughter.
Surveillance video from the mall in Burlington, around 105 kilometers north of Seattle, showed the gunman opening fire with a rifle, and the rifle was later recovered at the mall, said Cammock, commander of the Skagit county Multi-Agency Response Team.
The shooting comes less than a week after a man stabbed nine people at a mall in the central Minnesota city of St. Cloud before being shot dead by an off-duty police officer. The FBI is investigating that attack as a potential act of terrorism.
Police said Cetin is set to appear in court on Monday.