Huge clouds of black smoke billowed over Shanghai from multiple fires at a chemical plant Saturday that left at least one dead, according to state media and eyewitness video obtained by AFP.

The fire at a Sinopec Shanghai Petrochemical Co. plant in outlying Jinshan district broke out around 4:00 am, but was brought under control later that morning, according to state news agency Xinhua.

Aerial drone footage shared by a resident with AFP shows thick clouds of smoke hanging over a vast industrial zone as three fires blaze in separate locations, turning the sky black. 

"The fire at the scene has been effectively brought under control and protective burning is currently being carried out," Xinhua reported.

"According to our initial understanding, the fire has already caused one death."

The fire erupted as Shanghai, China's industrial engine and most populous city, gingerly resumes business after being sealed off for around two months to counter a coronavirus outbreak driven by the Omicron variant.

While the lockdown was officially lifted at the beginning of June, the snarling of supply chains and shutting of factories continues to have far-reaching consequences for the global economy.

At the petrochemical plant, an early morning explosion was heard by residents up to six kilometres (four miles) away, according to local media.

Videos on social media showed a large cloud of fire and ash billowing upwards.

"The whole area is completely incinerated," a shocked resident could be heard saying in the background of one video.

The refinery is very near the seafront in south Shanghai, as well as a wetland park. 

The Shanghai fire department said on Weibo that it had dispatched more than 500 personnel immediately after the incident around 4:28 am.

The Ministry of Emergency Management has dispatched an expert group to the scene, CCTV reported.

Reports have not stated a possible cause of the fire.