A manhunt was under way in the US state of Washington after a gunman opened fire in the make-up department of a Macy's store in a shopping centre north of Seattle, killing five people.

The Washington State Patrol said the five were shot on Friday night at the Cascade Mall in Burlington, about 105km north of Seattle.

Sergeant Mark Francis said authorities were searching for a "Hispanic male wearing grey" who was last seen walking towards a highway from the shopping centre.

This video image shows a suspect wanted by authorities [ Skagit County Department of Emergency Management via AP]

"We are still actively looking for the shooter. Stay indoors, stay secure," Francis said at a news conference.

A helicopter, search teams and K-9 units scoured the area for the rifle-carrying man.

Francis said four females were killed, and one male suffered life-threatening injuries. He later died in a Seattle hospital.

"One lone shooter" remained on the loose, he said. No motive was immediately known.

Tari Caswell told the Skagit Valley Herald newspaper she was in the Macy's women's dressing room when she heard "what sounded like four balloons popping".

"Then I heard seven or eight more, and I just stayed quiet in the dressing room because it just didn't feel right. And it got very quiet. And then I heard a lady yelling for help, and a man came and got me and another lady, and we ran out of the store," Caswell said.

An employee at a restaurant near the shopping centre said they "immediately locked the doors" when they heard of the mayhem on Friday night.

Stephanie Bose, an assistant general manager at Johnny Carino's Italian restaurant, in Burlington, told the Associated Press news agency the shooting happened inside Macy's department store. Her restaurant is just outside Macy's.

 

"He was trying to go to the mall and people were screaming," she said. "It was frantic."

It was not clear how many people were hurt in the attack. Medical workers entered the shopping centre to treat the wounded.

Governor Jay Inslee said in a statement the state patrol and local law enforcement were on the scene to locate the shooter and clear the area.

"We urge residents to heed all safety and detour warnings. Stay close to your friends and loved ones as we await more information and, hopefully, news of the suspect's capture," Inslee said.

Francis said survivors would be transported by bus to a nearby church.

Source: News Agencies