A violent tornado strikes multiple schools and destroys houses in Belvidere, Illinois, United States, causing over 450 casualties.

On the afternoon of April 21, 1967, a violent tornado tracked through Belvidere, Illinois, United States. The tornado struck just after students at the city's high school had been dismissed, as they were loading onto school buses. Many were flipped over and lofted, and the school itself sustained major damage. Throughout Belvidere, hundreds of homes suffered major damage, as did multiple businesses, in addition to the Chrysler plant and one of the city's two hospitals. 23 were killed directly by the storm, 13 of whom died at the high school alone. Past Belvidere, the tornado—which may have been a tornado family of multiple tornadoes following a single path—would strike another school bus in rural McHenry county before dissipating. Recovery was slowed down by snowfall days later. The tornado was one of three in Illinois to receive an F4 rating on the Fujita scale during the April 21 tornado outbreak.