In 1963, a secret passage was discovered in the Zhaoling Mausoleum of the Qing Dynasty in Shenyang. Why did the archaeologists almost die?

The three archaeologists who entered the mausoleum first were blocked by several huge stones after entering the tunnel for 100 meters. With no other choice, the three could only go back home, but at this time they encountered A big trouble was that in the narrow tunnel, the three of them couldn't turn around at all. They quickly passed the news to the ground command center. Later, with the help of everyone, the three people narrowly escaped death.