Seattle Police Department officials said on Twitter at about 10:30 p.m. that they were investigating a shooting at the Capitol Hill Park, ABC News reported.
Officials arrived on the scene to find three people with gunshot injuries, according to a statement.
"Despite lifesaving efforts by police and Seattle Fire, one man was pronounced dead at the scene," police said. "Medics transported the two other victims to Harborview Medical Center where one man later died, while the other remains in critical condition."
Police said they were searching for another man "who was involved but left the scene before officers arrived."
Seattle CSI and Homicide detectives will lead an investigation.