Three people were killed and four others, including a toddler, were wounded after gunfire erupted during the annual Bite of Seattle festival at Seattle Center near the Space Needle on Sunday.
Seattle police arrested one suspect and were searching for a second after investigators determined that two people were believed to have exchanged gunfire. Authorities recovered two weapons and said there was no ongoing threat to the public.
Police said two victims died at the scene and a third later died at a hospital.
Emergency responders identified the injured as a child, a woman who underwent surgery, a 23-year-old man and a 39-year-old woman.
UW Medicine later confirmed that all four patients it treated had sustained gunshot wounds. The woman remained in surgery, while the child, the 23-year-old man and the 39-year-old woman were reported to be in stable condition.
Seattle police described the incident as involving "multiple victims" and urged the public to avoid the area while officers secured the scene and gathered evidence.
The attack unfolded during the annual Bite of Seattle festival at Seattle Center near the Space Needle.
Founded in 1982, the free three-day event is one of Seattle's largest public festivals, drawing more than 350,000 visitors each year with hundreds of food vendors, live music performances and family activities.
Detectives are continuing to examine the circumstances surrounding the attack.