Firefighters were called to Wonderland Telford at the town park on Sunday evening to reports of a blaze in a 5m by 2m outbuilding which is used for storage of things like spotlights, hoses and polystyrene items which made it worst.
Alice Horne, who runs the 11 acre site, said: "I had just put my children to bed and had a call about 7.30pm to meet the fire service there.
"I've cried so much in the last 12 hours," said Alice. "I was just distraught at what we might lose.
"The one storey storage building is next to the hut with all the site electrics and if they had set fire to that it would have meant we cannot re-open on Saturday."
A frantic clean up operation is now under way to clean up the damage and replace items lost. Alice estimates that it could cost between £3,000 and £5,000 to get everything spick and span.
But she adds that the building, being close to the town park entrance and without the tree growth due later in the year, will be visible to visitors when the site reopens at 11am on Saturday.
Wonderland Telford is a children's park with a host of fairytale houses, six rides, a maze, sandpit and bouncy castles. It employs 15 people, which leaps to around 70 when the park is open.
"We've been closed for a long time, as we closed on December 23," said Alice. "It is our longest period of being closed.
"The park is not the same without all the families and children around. We are really looking forward to re-opening and seeing all the children around again."
Alice said Wonderland has events throughout the year and attracts tens of thousands of people to the site over the course of the year.
"We are building up to that, with our props ready to go out and of course some of them are no more."
"If it had been at the electrics store it would have completely ruined our event. Distraught is the only feeling we have."
But she added that the business finances were looking Ok, so they don't have to launch a special appeal. And they are not looking at increasing ticket prices.
"We are able to put it right and move on from it," she said.
"It will be the first time we've been able to host our Easter event since covid, so it is difficult to assess the impact on footfall. We might expect to see 1,500-2,000 families."
Alice urged people with information to contact the police if they have information about the incident.
"We have been having consistent issues in the park which makes it difficult for the family businesses here. The perpetrators seem to get more and more confident," she said.
Alice added that they would be "enhancing" their site security following the fire.
A spokesman for Shropshire Fire and Rescue Service said: "At 18:50 on Sunday, SFRS Fire Control received a call reporting a fire classified as property fire in Telford.
"Two fire appliances were mobilised from Telford Central. An operations officer was in attendance.
"Fire involving out building. Fire out building 100 per cent involved in fire. Crews used two hose reel jets and drag racks to extinguish fire."
A spokesman for Wonderland said: "Last night we were victims to an arson attack.
"Although scary, the situation was caught early and damage will not affect our opening.
"We plan to work round the clock to ensure we open on time on the 1st of April for our event.
"There are no serious hazards, it’s is mostly just a clean up operation."
West Mercia Police have been contacted for a comment.