At least six people are dead following an explosion at a pesticide factory in China so severe it trigged an earthquake.

The blast on Thursday afternoon at Chenjiagang Tianjiayi chemical plant in Yancheng, Jiangsu province, left dozens injured – many by flying debris – and shattered windows of nearby homes and a school.

Residents were helping to take the wounded to hospital, The Yangtse Evening Post reported.

Nearly 400 rescue workers and 86 fire engines were dispatched to the scene, the city government of Yancheng, which lies around 200 miles north of Shanghai, said in a statement. The cause of the blast is under investigation.

According to the South China Morning Post, the China Earthquake Administration reported a magnitude-3.0 earthquake in Jiangsu, likely trigged by the blast.

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A video posted on state broadcaster CCTV's website shows huge plumes of smoke spewing from a factory building and spreading over the area. Windows and garage doors appear to shatter at the moment of the blast.

Paramilitary police officers and a medical staff transfer an injured man following factory blast (AFP/Getty Images)

A man staying at a hotel about three miles from the explosion said glass in buildings along the entire street shattered, and at least four people in his hotel were wounded. He said a student at a nearby school was also hurt.

Some 31 people had been rescued, CCTV reported.