A fire at a transmitter site has affected television and radio broadcasts to thousands of homes.
The fire service was called to the blaze at the site in Bathampton, near Bath in North Somerset, just before 6am.
Crews have put out the fire - which they believe may have been started deliberately - but the damage caused a power cut, which engineers are working to fix.
Freeview television channels, BBC Radio Bristol, national analogue and digital radio channels have all been disrupted.
The BBC estimates that 80,000 homes in the area around Bath have been affected.
An Avon Fire and Rescue Service spokesman said: "This was a couple of sheds, or outbuildings, on fire, off Golf Course Road. We were called at around 5.45am and several appliances from Bath fire station are on the scene. I believe this may be affecting radio and possibly television transmissions in the area at the moment. Police have also been called as the early indications are that this fire may have been deliberately started."
Customers getting TV via Sky were unaffected, as were people in the south of the city whose TV signal comes from the Mendip transmitter near Wells.
A spokesman for Avon and Somerset Police said: "At this stage we believe it may have been started deliberately. It is not known exactly where the fire started, however we are appealing for anyone who saw people acting suspiciously in the area in the early hours of today to contact police on 101."
The transmitter is owned by the communications infrastructure and media services company Arqiva, which has engineers on site assessing the damage. The company said broadcast services including radio, television and mobile networks have been affected following the "suspected arson incident".
A spokesman added: "Due to fire the electricity supply has been isolated meaning that services have been temporarily switched off to enable safety work to take place. We are working to get services back to normal once the fire and police authorities have finished their initial investigation. We understand that people in the locality will be experiencing a loss in services and we are working on getting the transmitter back in full service so that the Bath area transmissions can be resumed."