Beijing (AFP) - A woman was killed after she plunged through flooring over an escalator in a Chinese department store, reports said Monday, thrusting her toddler to safety as she fell to her death.

Xiang Liujuan, 30, was holding her son in front of her as they went up the stairway on Saturday, the Wuhan Evening News said.

Security camera footage of the incident posted online showed a panel in the floor giving way as Xiang stepped off the escalator. As she fell half-way through she pushed her son forward, and a nearby shop assistant dragged him to safety.

But the escalator continued rolling, and several seconds later Xiang is seen disappearing downwards into the mechanism, despite one of the staff briefly grabbing her hand.

It took firefighters more than four hours to cut open the machine and recover the woman, who showed "no signs of life", the newspaper report said.

The footage shows employees standing at the top of the escalator as the mother and child approach.

Maintenance had just been carried out on the escalator at the Anliang department store in Jingzhou in the central province of Hubei, and workers forgot to screw the access cover back into place, the newspaper cited an unnamed source as saying.

The accident was one of the top topics on China's Twitter-like Sina Weibo on Monday with more than 6.6 million views.

Most comments expressed fury at the shop management.

"Why didn't the staffers stop customers at the entrance to the machine or just turn it off?" wrote one. "The department store is definitely responsible."

Others were moved by the woman's final actions.

"I was appalled when I saw her sink and at the same time felt the greatness of maternal love -- the mother wasted no time pushing the child out when it happened," said one.

China is prone to safety accidents as regulations and standards are often flouted and enforcement is lax, sometimes due to corruption.

In 2012, a nine-year-old boy was killed after he got stuck in an escalator at a Beijing department store as horrified shoppers looked on.

In July 2011, a 13-year-old boy was killed and more than 20 others injured when an escalator in a Beijing underground station suddenly reversed direction during the rush hour.