Two people were shot dead and three injured in what police call a “very targeted” attack at a camp for homeless people in Seattle.
Authorities said no one has been arrested and they are looking for two “persons of interest”.
The victims lived at the encampment, known as “the jungle”, south of downtown Seattle.
One woman died at the scene and one man who was brought to a hospital in Seattle later died.
Police believe it was “very targeted,” said Assistant Seattle Police Chief Bob Merner.
Seattle mayor Ed Murray urged people to stay away from the area, calling it an active crime scene.
Last November, Mr Murray declared a state of emergency regarding homelessness in Seattle and said he would pledge $7m (£4.9m) to the crisis.
“I can’t help but wonder, did I act too late?” he said at a press briefing on Tuesday.
He said the camp “has been unmanageable and out of control for almost two decades”.
Police are interviewing witnesses and stayed in the area overnight.
“We are working furiously to identify a suspect,” said Seattle police chief Kathleen O’Toole.
Ms O’Toole said she does not believe anyone else is in danger.