Firefighters were called to a former printing site in Scarborough yesterday evening after arsonists struck.
North Yorkshire Fire Service said it was alerted to a fire at the derelict building off Columbus Ravine at 7.50pm.
Crews sent to the scene found a fire burning inside the building, which measures around 300 square metres.
They wore breathing apparatus as they used a hose reel jet to put out the flames and then cleared smoke with high powered fans.
A spokesman said the fire had been started deliberately by youths.