This is the original radio broadcast of The War of the Worlds aired in 1938, which earned notoriety from the public and H.G Wells himself due to the mass public terror it caused. Orson Welles performed in this on the Mercury Theater radio show at a time when there was much public tension over the news about the Nazis in Europe, he and his co-writer planned to take advantage of this atmosphere.
As many as six million listeners heard the broadcast, but many had tuned in after the first 10 minutes, where the introductions to the performance had been made. At this time, the greatly popular Charlie McCarthy Show had just brought on their musical guest, which tended to make many to turn their wireless dials over to whatever else they could find. What they came to was a hauntingly realistic breaking-news style program, warning of poisonous gas clouds and strange objects landing from space. This was interspersed with musical numbers as the reports were 'only still coming in', convincing many of its authenticity.
This set about mass panic, as the broadcast was taken literally by roughly one and a half million of the viewers. Roads and public transportation was swamped as people rushed to flee the cities, apparently reporting they could smell the poisoned gas in the air.
The whole affair is one of the great hoaxes of the 20th century, aided by a little luck and fortunate timing. Certainly worth a listen for the quality performance also.