They were notified of the fire around 7.20 a.m. this morning.
A source has revealed that Workers have been performing maintenance on the site. On Friday and Saturday, the engineers worked on the external air conditioning units.
Around 7.20 a.m., fire crews were called to Copthorne Road in Crawley.
From the Wyevale Garden Centre to the Copthorne Hotel roundabout, the road is closed in both directions.
Initially, ten fire engines were on the scene, but an update at 8.55am revealed that West Sussex Fire and Rescue Service (WSFRS) had 17 vehicles on the scene, including five specialist vehicles.
The use of an aerial ladder platform has helped to tackle the blaze.
At 7.22am we were called to a fire at Acorn Health and Leisure in Copthorne Road, Crawley,” a WSFRS spokesman said.
We have crews from Crawley, Salfords, Reigate, Godsen, the aerial ladder platform from Horsham, two water carriers from Burgess Hill and Petworth, the control unit from Haywards Heath, and an East Sussex Fire and Rescue high volume pump so far.
WSFRS has been contacted for additional comment.
The cause of the blaze is under invesigation