Crews were called to Pelican Oils on Barracks Road on Sandy Industrial Estate at 10:20pm last night (Monday).
The cooking oil recycling centre contained 60 tonnes of waste oil and 500 tonnes of kerosene.
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Rescue teams arrived at the scene to find the two men standing on top of their car roof.
Rain and low cloud will clear to the south leaving a dry night with light winds.
Winds to ease through the evening allowing temperatures to fall steadily with a widespread frost developing.