LOS ANGELES: A manhunt was underway after a gunman killed at least three people and wounded two others late Friday during a shooting at a mall in the US state of Washington.

Police spokesman Sergeant Mark Francis said there was at least one suspect in the shooting at Cascade Mall in Burlington, describing him as a “Hispanic male wearing gray”.

Officials initially released a still from video surveillance of the younger-looking suspect holding what appears to be a rifle, before releasing a closely cropped image of the same still showing only the suspect's head and torso.

Francis told reporters that three women were killed and two men were wounded, with one suffering life-threatening injuries. He had earlier estimate the toll at four dead.

Police received calls around 6:58pm that shots were fired at the mall, located about 110 kilometres north of Seattle in the US Pacific Northwest state, Trooper Rick Johnson told CNN.

“Right now we can't assume anything. So they're still interviewing witnesses and trying to get a good idea of exactly what action to take next. We're just asking people to, obviously, stay away from the area. Stay inside and obviously report anything suspicious that they may see.”

The suspect was last seen walking toward the Interstate 5 highway from the mall before police arrived, Francis said on Twitter, adding: “We're actively searching for suspect, tracking leads, etc.”

The mall was evacuated and medics rushed to the scene to help the wounded after the mall was initially placed on lockdown and cleared, while multiple law enforcement agencies and sniffer dogs searched for the suspect.

Francis said survivors were being transported by bus to a nearby church.

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