Authorities have arrested a Turkish-born man suspected of shooting five people dead, including a teenaged cancer survivor, at a shopping mall in the US state of Washington.

Police named the suspect as Arcan Cetin, a 20-year-old resident of the nearby town of Oak Harbor, saying he was arrested late Saturday about 24 hours after the killings.

The FBI office in Seattle said it had no evidence the shooting was terror-related.

The gunman opened fire with a rifle in the makeup section of a Macy's department store late Friday, killing four women and a man, according to police. He later left the store on foot, triggering an intense manhunt.

A weapon was recovered at the scene of the violence, Cascade Mall in Burlington, a town of about 8,000 people some 110 kilometers north of Seattle.

Police are still trying to establish a motive.

The youngest victim was named as Sarai Lara, 16, who survived cancer as a young girl. Relatives named another victim as 52-year-old Shayla Martin, who worked as a Macy's makeup artist.

"We're really having a tough time right now," her sister Karen Van Horn told The Seattle Times.

Authorities had initially described the suspect as a Hispanic man in his late teens or early 20s.

Members of the public called in with numerous tips that helped lead to the arrest, police said, adding that Cetin's family was cooperating.

While Cetin was born in Turkey, he is a legal permanent resident of the United States, said Lieutenant Chris Cammock, criminal investigations chief for the Mount Vernon Police Department.

He is due in court Monday.

A Facebook page that appeared to belong to Cetin - and which has since been taken down - said he was born in the southern Turkish city of Adana.

It also said went to Oak Harbor High School, which is about a 50-km drive from Burlington, and had worked at a grocery store on nearby Whidbey Island.

In February, he posted a link to a Call of Duty first-person shooter videogame practice session, in an eerie foreshadowing of the real world violence he is suspected of perpetrating.

YouTube users posted lewd comments on that page and Cetin's Twitter page in response to the mall shooting.

Police said Cetin had one prior arrest, last year, for assault.