HONG KONG — It was a humid summer day in Jingzhou, a city in central China, and Xiang Liujuan, a 31-year-old mother, had gone to the mall to relax.

Ms. Xiang never cared much for fancy clothes or high-end makeup, her relatives said, and on Sunday, as on most days, her attention was focused elsewhere: on her 2-year-old son, who was running around a mall playground in a T-shirt and blue shorts.

But after Ms. Xiang and her son had left the playground and stepped onto an escalator, frantic shouts broke out. A floor panel at the top of the escalator was loose. Ms. Xiang tried to avoid the resulting trap door, but she fell in. As the machinery swallowed her, she spent her final moments pushing her son to safety.

Ms. Xiang’s death, caught on mall security cameras, has provoked a furious response in China. Social media users have accused the mall of murder, and The People’s Daily, the main newspaper of the Communist Party, called on Tuesday for a thorough investigation.