Reports on the death toll from the shooting at the Seattle Center vary between two and three fatalities.
Estimates regarding casualties also differ, with some accounts reporting four injuries while others suggest five victims were hurt.
Among those injured in the incident was a 2-year-old boy.
The deceased have been identified as a 19-year-old man and a 44-year-old man, though some reports list a 56-year-old woman as injured rather than deceased.
Authorities believe two suspects were involved in the incident and were firing at one another.
While some reports indicate one suspect was arrested, others state that police have not yet confirmed any individuals are in custody.
The shooting occurred at approximately 6 p.m. local time.
The violence took place at the Seattle Center during the Bite of Seattle food festival.
Police recovered two firearms from the scene.
One report indicated that no surveillance cameras were located in the immediate area of the shooting.
Seattle Mayor Katie Wilson characterized the event as 'an act of horrific violence.'
Assistant Police Chief Tyrone Davis stated that officers arrived on the scene within seconds.
Witness Faith Adia Hunter reported, 'We were right next to him when it started, so we took off running.'
Witness Estan Wakonabo described the chaos, stating: 'People were hiding, were pushing, people were falling on the ground, baby strollers were falling.'
Witness Nick Bate noted, 'At first, I thought there were fireworks, and then everybody flooded and ran past us.'
Witness Todd Behrends stated he heard what sounded like several rounds of shots.
This year marked the 42nd edition of the Bite of Seattle festival.
The festival typically draws approximately 350,000 attendees over a three-day period.
No description of the outstanding suspect was immediately available.