Channel 4 has been forced off air this evening due to an evacuation at Red Bee Media, the company responsible for the broadcaster's playout.
The problem has also affected More4, 4Music, Film4 and other stations in the Channel 4 stable, while Channel 5 and its sister channels were also off air for a brief period. BT Sport 3, in addition to BT Sport's UHD channel, are also down.
According to reports on social media, Red Bee's building at White City in West London has been fully evacuated amid a possible fire alarm.
The problems were first noticed by viewers at around 6.30pm, with Channel 4 having been stuck on a frozen screen ever since.
In a short message on Twitter, Channel 4 said: "Channel 4 and More 4 are currently off air due to a technical problem. We are working to restore them as quickly as possible."
Channel 4 finally resumed broadcasting at 8.07pm, albeit without audio, with a programme called Britain's Forgotten Wars with Tony Robinson, which was not scheduled to be broadcast until 8.20pm.