Tangshan was one of the industrial cities in China at the time, and an estimated one million people lived there. The maximum intensity of the earthquake was Extreme on the Mercalli scale. In minutes, 85 percent of the buildings in Tangshan collapsed or were rendered unusable, all services failed, and most of the highway and railway bridges collapsed or were seriously damaged. The official report claimed 242,769 deaths and 164,851 serious injuries in Tangshan, but when taken into account the missing, the injured who later died and the deaths in nearby Beijing and Tianjin, scholars accepted at least 300,000 died.

The city had been built on soft soil that was often further softened when the nearby Luan River flooded. When the ground shook, the soil essentially swallowed buildings up. In the city of Tangshan, people were trapped under rubble, and coal miners in surrounding areas were crushed by the collapsing mines. Several strong aftershocks further destabilized the region. When the tectonic plates stopped shifting, all of the methods of transportation into the city were destroyed.

This lack of regard for the people and obvious concern only for themselves would ultimately be the undoing of the Gang of Four. The earthquake was simply the last straw after a series of careless power grabs that the Gang of Four had made. The devastation from this massive earthquake finally brought about exactly what Mao had feared, though he would not live to see China reject his Cultural Revolution.