Four women have been shot dead and a man critically injured at a shopping centre in Burlington, Washington state.
Authorities have released an image of the suspected gunman, who fled the scene armed with a rifle.
Nearby stores and the Cascade Mall have already been evacuated and police have asked the people to stay away. The reason for the assault is unclear.
The suspect, described as a “Hispanic male wearing grey”, was seen heading towards the Interstate 5 motorway.
Crisis medical teams had entered the shopping centre “to attend to injured” and people were being evacuated into a nearby church, he said.
Mr Francis said the gunman had left the scene before police arrived and was last seen walking towards a motorway.
Emergency management officials have told residents to stay indoors with their doors and avoid the area near the Cascade Mall. Motorists are being urged to keep nearby major roads clear.
The FBI, which will be assisting in the investigation, says there is not any evidence that further attacks are planned in Washington State.
Burlington is about 65 miles (105km) north of Seattle.