Three people were killed and four others, including a two-year-old child, were injured after a shooting at the Bite of Seattle food festival in downtown Seattle on Sunday, according to police.
The incident unfolded at around 6:00 p.m. local time near the Seattle Center during the final day of the annual event.
Police said one suspect, described only as a young person, has been taken into custody, while officers continue searching for a second suspected shooter.
Officials said they believe the two suspects were shooting at each other.
Authorities added that there is no ongoing threat to the wider community as the investigation continues.
Assistant Police Chief Tyrone Davis said officers recovered two firearms at the scene and are interviewing the suspect in custody.
Police declined to disclose a motive or provide a description of the second suspect.
Two victims died at the scene, while a third later died in hospital, bringing the death toll to three.
The four remaining injured victims were reported to be in stable condition, while another injured person declined hospital treatment.
Police later identified those killed as a 19-year-old man, a 44-year-old man and a 56-year-old woman.
Detectives from homicide and gun violence reduction units remain involved in the investigation.
Seattle Mayor Katie Wilson described the shooting as "an unbelievable tragedy, and a horrific act of violence."
She said the city had experienced several major gun violence incidents within days and expressed condolences to those affected.
Washington Governor Bob Ferguson and Representative Pramila Jayapal also condemned the shooting, describing it as senseless violence and offering support to victims and first responders.
The Bite of Seattle festival, held near the city's Space Needle, attracts hundreds of thousands of visitors each year.
Videos shared online showed festival attendees and visitors seeking cover as gunfire erupted, while witnesses described hearing multiple shots before fleeing the area.
Authorities have urged the public to avoid the scene while investigators continue gathering evidence.