Fire crews had requested the Environment Agency to attend the fire at a building on Collaton Lane in Tavistock, to help control a diesel spillage.
Western Power has also been at the site and disconnected the electricity to help make it safe.
At 0700, a cordon has been put around the area and fire crews were monitoring the incident from a safe distance because of the volatile nature of acetylene cylinders.
More top news
Luke Castiglione has the full forecast. Showers drying up but further rain on the way....
Friends remember "amazing" Adam Pritchard, who died after apparently plunging down down a sharp drop while cycling with his sister.
Rain and the ensuing mud hasn't stopped thousands of people enjoying Glastonbury festival