Twin 80-year-old brothers were apparently overcome by carbon monoxide while working on an antique car in a closed garage in Chehalis and died.
The Lewis County sheriff's office says the wife of one of the men found them Sunday evening when she returned home from a neighbor's house.
The other brother was visiting from Rainier, Wash.
The sheriff's office says the men were working on the car's exhaust.
When fire department emergency responders arrived, their carbon monoxide detectors showed a high level of the deadly fumes.
One brother was declared dead at a Centralia hospital and the other at a Seattle hospital.