Officers responded to shots fired just before 1 a.m. local time, Renton police spokeswoman Sandra Havlik said.
Upon arrival, officers located several victims. One person died and up to five people were treated at the scene by emergency personnel, Havlik said.
Initial reports indicate the shooting stemmed from a dispute outside a large gathering, possibly resulting in more than one suspect shooting.
It was not an active shooter situation, Havlik noted. The investigation is ongoing.
Renton is a city of about 106,000 about 12 miles south of Seattle.