According to West Sussex Fire and Rescue Service, crews were first called to Holmbush Lane just 1.10am and were still in attendance as of 10.20am.
A spokesperson said: "There may be smoke in the area, we are advising that residents nearby keep their windows and doors closed."
The fire service said a crew from Worthing station were still at the scene for a 'watching brief', whilst 'pockets of fire are still present'.