THIRTY-five caravans were burned to shells in a blaze that kept firefighters busy for four hours on Monday night.
More than £10,000-worth of damage was caused but no-one was injured in the fire at the Coppy Clough caravan site on Dineley Street, Church.
Tony Spencer, sub-officer at Hyndburn Fire Station, said: "What made the incident more hazardous for us was the presence of gas cylinders throughout the site. They were exploding unexpectedly and this made the fire even harder to quell.''
The fire - which police are treating as suspicious - raged from 9.30pm until 1.30am.
Four fire crews, two from Accrington and two from Great Harwood, used four water jets and two hosereels to fight the fire with water from the nearby canal.
Mr Spencer said: "We squirted water from behind the walls until we were confident it was safe to enter. There were 35 caravans but now it's just 35 chassis."
The site is now a chaotic scene of charred metal and debris.
Mr Malcolm Wood, the owner of the site, said vandals had targeted his business before but he could not comment on this fire.
Detective Sergeant Paul Murphy said: "If anyone has any information about the fire they should contact Accrington CID."