A total of 18 fire crews, including Baldock and Stevenage, put out a blaze 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 attended the scene to tackle the fire.
In addition, three jets and one aerial ladder platform were used.
There have been no injuries and it was confirmed at 2.50pm, today, the fire has been put out.
Several fire service vehicles are still at the site, according to HCC.
The Leavesden-based studios have also been involved in the production of The Dark Knight, Inception, Star Wars Episode I: The Phantom Menace and Jason Bourne.
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