A total of 18 fire crews, including from Royston, are attending a fire at the studios where all eight Harry Potter films were made.
Hertfordshire County Council's Fire and Rescue Service were called at 11.29pm yesterday to the 80-hectare Warner Bros Studios complex in Leavesden.
HCC says 18 fire engines and support vehicles are still at the scene as crews continue to tackle the fire.
In addition, three jets and one aerial ladder platform are in use.
There have been no injuries due to the fire.
The Leavesden-based studios have also been involved in the production of The Dark Kight, Inception, Star Wars Episode I: The Phantom Menace and Jason Bourne.
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