Fire crews were called early on Saturday as a shed and fence were alight at the Highbridge Caravans site.
A Devon and Somerset Fire and Rescue Service spokesman said the blaze posed significant danger to firefighters, because of gas cylinders on site.
It is believed the fire quickly spread to the caravans. The fire brigade received more than 60 emergency calls.
About 160 caravans have been destroyed in a fire and series of explosions which ripped through a storage yard.