The explosion shattered windows and doors of buildings in a three-kilometre radius. (Representational)

Two people have been killed and another 12 are missing after a huge explosion rocked a gas plant in central China on Friday, state media said.

According to state broadcaster CCTV, 18 people were seriously injured in the blast, which happened at 5:50 pm local time (0950 GMT).

The explosion shattered windows and doors of buildings in a three-kilometre (1.9-mile) radius, state media said.

Xinhua said the blast occurred in the air separation unit of the Henan Coal Gas Group factory and not in the gas tank areas, citing a source in the Yima city government. All production at the plant has been stopped.

"Many windows and doors within a three-kilometre radius were shattered, and some interior doors were also blown out by the blast," state broadcaster CCTV said on its Twitter-like Weibo social media account.

Local media showed amateur videos of a massive column of black smoke billowing from the factory and debris littering the roads.

Other images showed the doors and windows of homes blown out and shuttered shops with dented metal fronts.

A bloodied man was seen being helped out of a van in a video posted on social media.

AFP could not immediately verify the authenticity of the footage.

Industrial Accidents

Deadly industrial accidents are common in China, where safety regulations are often poorly enforced.

In March, an explosion at a chemical plant in eastern Jiangsu province killed 78 people and injured hundreds.

The powerful explosion in the eastern city of Yancheng toppled several buildings in the industrial park, blew out windows of nearby homes and even dented metal garage doors.

Authorities detained two dozen people in connection with the March 21 blast, which prompted the government to order a nationwide inspection of chemical firms.

A week after that explosion, seven died after an explosion at an electronics component manufacturer in the same province.

In November, a gas leak at a plant in the northern Chinese city of Zhangjiakou, which will host the 2022 Winter Olympics, killed 24 people and injured 21 others.

Leaked chloroethylene came in contact with a fire source causing the explosion, authorities said in a February report, which also claimed the Chinese chemical firm responsible for the accident had concealed information and misled investigators.

In 2015, China suffered one of its worst industrial accidents when giant chemical blasts in the northern port city of Tianjin killed at least 165 people.