Los Angeles (AFP) - Police searched Saturday for a shooter who killed five people at a shopping mall in the US state of Washington in the latest chapter of America's epidemic of gun violence.

The gunman opened fire with a rifle in the makeup section of a Macy's department store, killing four women and a man, police said.

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

The shooter -- described as a Hispanic man in his late teens or early 20s -- later left the store on foot, and his whereabouts remained unknown.

A weapon was recovered at the store in Burlington, a town of about 8,000 people some 70 miles (110 kilometers) north of Seattle.

Police released screen-grab photos of the suspect from mall security camera footage to help the public identify him.

"I don't know what his motivation was to do this," Chris Cammock, police chief in the larger nearby town of Mount Vernon, told a news conference. "But I certainly plan to find out through the investigation, to the best of our ability."

He said police were not looking for anyone else as part of their probe.

Burlington Mayor Steve Sexton's voice trembled as he noted that the randomness of gun violence in America -- which causes an estimated 30,000 deaths a year -- had hit his small town.

"This was a senseless act, the world knocking on our doorstep. It came to our little community," Sexton said.

Police provided a still from video surveillance of the suspect showing only his head and torso, though the full picture, published by local media, showed him holding what appeared to be a rifle.

The shooting came amid fierce debate in America over gun control laws. It is a hot issue on the campaign trail ahead of the November 8 presidential election.

Police received calls around 6:58 pm Friday (0158 GMT Saturday) that shots were fired at the mall.

The shooter had walked in without a weapon, and appeared on security cameras about 10 minutes later with a rifle, said Cammock.

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The suspect was last seen walking toward a highway from the mall before officers arrived, police said.

The mall was evacuated, police swarmed the area and medics rushed to the scene after the mall was initially placed on lockdown.

"We are devastated by the tragic events that occurred last night at Cascade Mall," Macy's said in a statement on its Facebook page Saturday.

"We are working closely with local law enforcement authorities as the investigation continues to unfold."

- 'Shot after shot after shot' -

At a vigil held for the victims Saturday morning in Burlington's Maiben Park, Kelly Couture, who exited the mall through a Target store as the chaos was unfolding, told The Seattle Times there were "just sirens and people were yelling and running out of the building."

Witnesses told KOMO News that a shooter walked into the Macy's store and opened fire. Nearby businesses were evacuated, the television station added.

"I hear one shot and then stand kinda still and like two, three other people start running out saying 'gun' and then shot after shot after shot," said Armando Patino, who was working at a cellphone store.

"I turn around and run to the store. Some people didn't know where to go. I just moved them into the store," he added.

"We went in the back where we have a door and everything and we just stayed there until they told us to evacuate."

Multiple law enforcement agencies and sniffer dogs were searching for the suspect.

Police took hours to clear the sprawling building.

Cammock said police have so far interviewed around 20 people about the shooting.

The mall said it would stay closed on Saturday as a mark of respect for the victims.