Firefighters are tackling a large fire at a commercial unit in Maylands Avenue, Hemel Hempstead.
Hertfordshire Fire and Rescue Service were called to the Progression Center at 3.51pm to a building fire on Mark Road.
The first floor was on fire and the roof had partially collapsed.
Fire crews confirmed there are no casualties reported.
Six crews from Hemel Hempstead, Kings Langley, Hertford, St Albans, the Watford aerial ladder and a command support unit were on the scene.
Herts Fire Control has now scaled back their presence to three fire engines and the aerial ladder from Watford.
Hertfordshire Police have closed Mark Road whilst firefighters get the fire under control.
If anyone has any information about the fire please email firstname.lastname@example.org