Crews from Cwmbran, New Inn, Maindee and Aberbargoed were called to the outbreak off Avondale Road, Cwmbran, at 00:50 BST on Wednesday.
It took firefighters over an hour to bring the blaze under control.
South Wales Fire Service has confirmed that a large quantity of gas cylinders were involved in the fire.
Officers from the fire crime unit will be at the site on Wednesday morning to collect the cylinders.
The fire is understood to have started accidentally.
A fire at a storage site in Torfaen has destroyed 18 touring caravans and left 13 others with heat damage.