The first two-thirds of the one-hour broadcast was presented as a series of simulated news bulletins. The first news update interrupted a program of dance music to report that a series of odd explosions had been spotted on Mars, which was followed soon thereafter by a seemingly unrelated report of an unusual object falling on a farm in Grover's Mill, New Jersey. Martians emerged from the object and attacked using a heat ray during the next interruption, which was followed by a rapid series of news reports describing a devastating alien invasion taking place across the United States and the world. The illusion of realism was furthered because the Mercury Theatre on the Air was a sustaining show without commercial interruptions, and the first break in the program came almost 30 minutes into the broadcast. Popular legend holds that some of the radio audience may have been listening to Edgar Bergen and tuned in to "The War of the Worlds" during a musical interlude, thereby missing the clear introduction that the show was a drama, but recent research suggests this only happened in rare instances.
In the days following the adaptation, widespread outrage was expressed in the media. The program's news-bulletin format was described as deceptive by some newspapers and public figures, leading to an outcry against the perpetrators of the broadcast and calls for regulation by the Federal Communications Commission. The episode secured Welles' fame as a dramatist.