Screenshot from a surveillance video footage shows the moment when the woman falls into the gap that suddenly appeared on the escalator. She is seen holding her son to save his life in a shopping mall in Jingzhou city in central China's Hubei province on July 26, 2015. [Photo: Xinhua]

A woman was killed in a freak accident, when she fell into a sudden fissure that appeared at the top of an escalator in a shopping mall in Jingzhou city in central China's Hubei province on Sunday.

The 30-year-old woman fell into a gap that suddenly opened as she was about to step out of the escalator.

The woman was with her son when the accident happens. She clung to the edge of the collapsed escalator and held her son up to save his life.

Some staff members in the mall grabbed the boy and rescued him.

But they were unable to pull out the mother.

The woman's body was found after around four hours.

Local police have started investigating the cause of the accident.

Meanwhile, the surveillance footage from the scene of the accident has become the most-searched video on China's social media.

The tragedy has triggered netizens to question whether the escalator was properly operated and maintained by the shopping mall.