"When officers arrived there were still shots being fired," said Federal Way police spokeswoman Cathy Schrock.They found two injured men on the ground in a parking lot. One of the men reached for a gun as police moved in to assist the two, she said.
At that point, officers opened fire. The suspect died but police said it wasn't immediately clear if it was from their gunfire.
The other man on the ground and a third man in the parking lot were found dead.
In a search of the complex, police found a fourth man dead in one apartment and a slain woman in another unit. Schrock said police were trying to determine if the woman was accidentally hit by gunfire.
A total of eight officers fired their weapons, Schrock said. All have been placed on administrative leave, per standard policy, as the investigation continues.
There was no immediate word what set off the shooting.
"We're gonna continue to go door to door in hopes that we can find some additional witnesses, and hopefully we won't be finding any more victims." Schrock said. "We still don't have any idea what started this disturbance tonight."
After police flooded the area and carried out searches, authorities said they were confident there were no more casualties from the shooting.
They said they did not think another shooter was on the loose or that there was an immediate threat to the public.
There were no reports of any officers being injured, and the names of the five people who were killed were not immediately available.
Federal Way is about 20 miles south of Seattle.