Police rushed to the scene after reports of a shooting with “multiple victims” near the scene of protests over the surprise victory of Trump in the US presidential election.
Four men and one woman were hit as a gunman opened fire in the city centre at about 7pm local time – 3am in Britain.
Two of the victims are in a life-threatening condition.
The shooter is still at large.
“Detectives are on scene and have closed several streets”
Witnesses said a group of people were arguing when the gunman fired into the crowd in Third Avenue.
The city centre was already crawling with cops due to an anti-Trump rally, which started at the Westlake Mall earlier.
The rally turned into a march and was proceeding down nearby streets at the time of the shootings.
At least one victim was a bystander, Seattle police Assistant Chief Robert Merner said.
The Seattle Fire Department said on Twitter that crews were treating five patients with gunshot wounds – one of them with life-threatening injuries.
The shooting is not thought to have been sparked by the protest.
Seattle Police said: “Police found five victims on the street in front of a convenience store and at an adjacent bus stop.
“One man was taken to Harborview Medical Center in critical condition.
“The four other victims – one woman and three men – were transported with non-life-threatening injuries.
“At this time, the shooting is not believed to be connected to earlier demonstration at Westlake.
“Detectives are on scene and have closed several streets in the area as police collect evidence and search for witnesses.
“Police are still gathering information about the suspect – who is believed to be an adult male.”