Orson Wells terrified all of America in 1938 with his Halloween radio play of War Of The Worlds. Even though he was well known for his radio theatre, people thought it was real and it caused national panic. They were already nervous with war about to break out. What convinced them was the way it was broadcast like a news report.
Orson Wells was all innocent at the time, but 20 years later he admitted it actually was done to scare people, because he didn't like the fact that people believed everything that came out of this 'new magic box' called the radio.