A 66-year-old Bellevue woman died Sunday when a fire broke out in her first-floor condo at Windsor House, a residential complex located just west of Bellevue Square.

Investigators suspect the woman, identified by her neighbors as Judy Olson, may have started her mattress on fire by smoking in bed.

The building’s automatic alarm notified emergency dispatch of the fire around 6:30 p.m.

The fire was contained to the victim’s unit, and crews quickly put it out, according to Bellevue Fire Department spokesman Eric Keenan.

Firefighters found the woman collapsed and unconscious on her kitchen floor, suffering from burns and apparent smoke inhalation, Keenan said.

Rescuers tried unsuccessfully to resuscitate the victim. She was pronounced dead at the scene.

Investigators discovered clothing materials in the kitchen sink that the victim may have removed during the fire.

“You never know what state they’re in when they’re overwhelmed like that,” Keenan said. “It’s hard to know for sure what they did.”

Windsor House was built in 1982, and none of the 62 condos there have sprinklers.

The fire set off a smoke detector in Olson’s unit, which in turn activated an alarm for the entire complex.

Resident manager Jim Myers located the fire using the alarm system’s control panel and reportedly ran outside to Olsen’s condo, where he spotted flames inside but could not gain access to the unit.

Another resident, Ward Tanneberg, tried to enter Olson’s condo through the front door, but was overwhelmed by smoke.

“When I cracked open the door, smoke just poured forth,” Tanneberg said. “It was at the floor level.”

Tanneberg said he called into the unit, but heard no response.

Windsor House residents were forced to evacuate the building for two hours. Neighbors invited many of the occupants into their homes while fire crews investigated the incident.

“There were a lot of compassionate people out there,” said Joyce Shaffer, who lives in the complex. “It’s really heartwarming how we got taken in by the community.”

Olson was head of the committee for social events at Windsor House and was involved with a bridge group there. She was also part of the building’s emergency response team.

“She was a very pleasant woman, and very active,” said resident Dixie Tanneberg.

Shaffer remembers Olson as a “lovely and energetic woman” who lived alone. She described the fire as “depressing” and “sobering,” but also “touching” because of the help from neighbors.

“There’s that combination of sadness about the death and incredible gratitude that we’re alive,” Shaffer said. “It was so touching. We spent many hours in the cold, and people nearby took us in.”

Joshua Adam Hicks can be reached at 425-453-4290.