This is the terrifying moment a mother and her two-year-old son are knocked off their feet when a gas explosion sends a sheet of flame shooting through their kitchen.

The mother had been cooking when a gas pipe fell away from the hob, triggering the massive blast at her home in Zhuji, Zhejiang province, China, on October 14.

Shocking home security CCTV footage shows how the explosion sends flames and debris from one side of the kitchen to the other without warning.

The blast is so powerful it blows out the kitchen cabinets, burying the boy under the rubble.

With astonishing courage, the 38-year-old mum ignores the agony of her own injuries to dive back into the blast zone to pull her terrified son to safety.

The skin on her arms and legs can be seen gruesomely hanging off where she took the full force of the flames.

Screaming in agonising pain, she manages to pull her phone down from a wine rack and tries to call for help.

With her son's help, she dialled a number on her mobile, and moments later, neighbours apparently came to the apartment and led the mother and son to safety.

It later emerged that the mum suffered third-degree burns over up to 70 per cent of her body and is recovering in a hospital ICU after emergency surgery on October 19.

Her husband, named locally as Mr Xu, said her throat had also been injured by flying debris from the explosion.

Amazingly, her son survived the blast with barely a scratch and was treated for shock.