Hundreds of tourists visiting Warwick Castle on the last day of the Easter break were evacuated when a flaming cannonball destroyed the roof of a historic boathouse.
More than 30 firefighters were sent to the scene on Friday evening and the cause of the fire is being investigated.
Visitors watched as the burning cannonball was fired from the world's largest working siege machine in the daily display, the Daily Telegraph reports.
Sparks from the cannonball, which was fired from the wooden trebuchet, ignited the roof of the ancient boathouse.
Holidaymaker Heather Taylor was visiting the attraction with her six-year-old son Ethan for the cannonball launch.
Speaking to ITV News, the 42-year-old said: "The trebuchet launched the flaming cannonball but as it flew almost over the boat house sparks could clearly be seen coming off it and the high winds must have sent them onto the roof of the boathouse.
"There was a lot of panic and people were scrambling up the bank because they had no idea if the fire would spread. The place was packed with lots of young children and families. We were all evacuated and it was quite scary."
She added: "It was shocking how fast the fire took hold. The cannonball actually appeared to land behind the boat house but it was obviously too close. It's such a shame because we the boat house has only just been re-thatched and we watched a chap thatching it before the big show. It's a listed building so it's a big loss."
No injuries were reported and Warwick Castle was unaffected by the fire.