It is probably the most infamous radio broadcast of all time: Orson Welles’ Halloween 1938 dramatisation of H.G. Wells’ “The War of the Worlds”.
Welles transplanted the story from England to Grover’s Mill, New Jersey, and told it as a series of news reports, keeping the tension and hysteria of it all steadily rising. It terrified audiences at the time – like a hell of a lot of Welles’ work it is arguably a great work of art, and an enormous prank at once.
Whether or not there was panic during the broadcast, there was considerable outrage afterwards – how that has to do with the alleged ‘cruelty’ of it, and how much with people just hating to be fooled is an open question.