Fire officials say Kennewick fire crews followed department protocol before they left the scene of an apartment fire last month that eventually rekindled.
The Tri-City Herald reports that the investigation into two fires Feb. 12 found firefighters made sure the first blaze was out before leaving.
No residents were injured. One firefighter was treated at a local hospital.
Kennewick Fire Chief Neil Hines says there were no breaches of fire department policy.
The first blaze started shortly before 8:45 p.m. The fire was under control within an hour and the last fire truck left the scene at 11:18 p.m.
Crews were called back around 3 a.m. as a second fire engulfed the building's roof.
Officials said the second fire started somewhere in the attic.