The provincial government had scrambled 700 firemen from across the province to join the rescue operation, authorities said.

The tornado brought gusts ­recorded at 125 km/h and was ­accompanied by hail stones the size of fists. On the Saffir-Simpson Hurricane Wind Scale where 1 is the lowest and 5 the highest, the tornado which hit is a Category 1 with winds ranging from 119 to 153 km/hr.

Although local meteorological authorities issued extreme weather alerts and began an emergency evacuation shortly after the tornado struck, it was too late to prevent heavy casualties in the area of two million residents.

Many witnesses said they were caught unprepared. “I was driving when trees along the road suddenly fell down,” one witness told China News Service. “My car was swept by strong winds into a river and I was lucky enough to manage to get out of the car and escape to safety,” he said.

Another villager said she was outside her house when it “went dark all of a sudden”. “I ran back to my house when tiles and bits of the roof were hurled down by the wind. The house collapsed within seconds in a deafening noise and I was fortunate enough to be able to crawl out of the debris,” she said. Pictures on social media showed houses flattened and the injured being treated in makeshift hospitals. Most roads leading to the tornado-hit areas were cut off with no electricity, telecommunications signals or fresh water.

Provincial authorities said the disaster had caused severe damages across coastal Yancheng. Dozens of the injured were treated in nearby hospitals, while hundreds of others were rescued.

Local weather agencies said the tornado was of an intensity rarely seen in China and warned that heavy rainstorms and gusts might continue into the night, causing greater damage.

China Central Television said several factory warehouses in ­Funing containing toxic chemicals were severely ­damaged. Most workers were rescued.