It took fire crews over two hours to quell a blaze in a scrap car compound at Epworth in the early hours of Monday.
A large number of vehicles were destroyed in the fire that flared up after 2am within locked premises off Sandtoft Road.
An investigation was launched but a fire spokeswoman said the fire is believed to have been caused accidentally.
She said: “Several vehicles in a yard measuring 20 metres by 10 metres were well alight when crews arrived at the scene.”
Three engines manned by crews from Epworth, Crowle and Goole dealt with the blaze, that had also begun to spread to some outbuildings.