At about 1:15 a.m. this morning (Monday) Sunnyside firefighters rushed to a blaze at 520 North Fourth Street.
The home has been condemned for more than a month, according to Assistant Fire Chief Lloyd Hazzard, and there wasn't any power to the structure.
He said the blaze was set inside the home and investigators found traces of an ignitable substance after extinguishing the fire.
"Samples (of the traces) have been sent to the crime lab," shared Hazzard.
He said the evidence collected at the scene leads investigators to believe the fire was an arson.
Approximately $12,000 damage was caused to the home, which was vacant. The Yakima County Assessor's Office has the homeowner listed as Simon Estrada.
The Sunnyside Police Department is assisting in the investigation.
Anyone with information about the case is urged to call the Sunnyside Fire Department at 837-3999 or the Sunnyside Police Department at 836-6200.
In other Sunnyside Fire Department news, firefighters since last Thursday have responded to 20 aid calls. Eight patients were taken to the hospital.
Firefighters have also responded to two automatic alarms that were false calls. They extinguished an illegal burn in the 400 block of Madison Avenue, as well.