It was not clear if any officers had heard the gunshot from inside the bunker, she said.
The raid ended a tense week for law enforcement officials who tried to track down Keller, a gun enthusiast described by his family as having a "survivalist mentality." That Keller was likely armed and on the loose in an extremely popular hiking and mountain-biking area east of Seattle kept many people on edge.
"There's been a huge sigh of relief," Larson said. "Our people are out safe, and the trails are now safe for the community to use."
Keller spent eight years building the bunker into the side of Rattlesnake Ridge, police said. It was thoroughly camouflaged and had multiple levels. Photos of the inside of the bunker, released by the King County Sheriff's Office, showed a shelf full of ammunition boxes stacked inside Ziploc bags.
SWAT squads spent a grueling seven hours on the mountainside Friday morning, virtually crawling over dangerously steep terrain slick with mud from recent rains, before they found the bunker. A number of officers were treated intravenously for dehydration, and one broke his ankle, Sheriff's Sgt. Cindi West said.
After long shifts, the officers appeared exhausted, their faces smeared with camouflage paint, as they rode down the mountain in sport-utility vehicles or armored carriers to be replaced by fresher teams.
SWAT officers who kept watch on the bunker through Friday night said they saw lights going on and off, and they believed its occupant had everything necessary to remain inside for a long time - including a generator, food, gas mask, bullet-resistant vest, and many guns.
Photographs found in Keller's home after the killings gave authorities an idea of where it was; in one picture that they enhanced, detectives could make out buildings in nearby North Bend. Combined with reports from alert hikers who remembered seeing his faded red pickup truck at the Rattlesnake Ridge trailhead, the sheriff's office sent experienced trackers to the area, where they found off-trail boot prints confirming their belief that he was somewhere on the ridge.
They could smell smoke from his woodstove before they found it.
Authorities pumped tear gas into the structure Friday, but it failed to flush the occupant - either because it did not penetrate deep enough into the structure, or because the person had a gas mask.