Klamath County Fire District 1 (KCFD1) was dispatched at 9:55pm last night for smoke in the area of the 1600 block of Oak st in Klamath Falls. The incident rapidly changed to a commercial structure fire with multiple vehicles next to the building burning at the address of 515 Spring St. The first arriving fire engine arrived to find heavy smoke and flames coming from the south side of the structure. The structural integrity of the building was compromised and made it unsafe for fire crews to enter the building. Crews made fire attack from outside the structure with master streams delivery a large amount of water. KCFD1 was assisted by Kingsley Field Fire. An occupant living in an RV on the property was injured and transported by KCFD1 to Sky Lakes Medical Center with minor injuries. The occupants dog perished in the fire. The fire is still under investigation, but appears to have started in an RV parked next to the building. The fire destroyed an approximate 10,000 square foot warehouse and multiple vehicles. Estimated loss is around $250,000. Crews were still on scene today, extinguishing the fire.