WUHAN, July 26 -- A woman was killed on Sunday morning after falling through a gap that suddenly opened at the top of an operating escalator in a Chinese shopping mall, with horrifying CCTV footage of the incident going viral online.

The clip shows the 30-year-old, named by the local government as Xiang, briefly cling to the edge of the gap while holding her young son out to be rescued by a member of staff in the mall in Jingzhou city, Hubei Province.

The municipal government of Jingzhou said the accident happened at about 10 a.m. The child escaped unharmed but the mother was found dead inside the escalator later.

One staff member tried to grab Xiang but failed.

The accident became the most searched-for topic on Sina Weibo, the Chinese equivalent of Twitter, on Monday, prompting a flurry of questions about whether the escalator had been properly maintained and operated.

Local authorities are investigating the case.