The death toll from a huge explosion at a chemical plant in eastern China surged to 47 Friday, making it one of the country's worst industrial accidents in recent years. The plant has a long history of safety violations.

More than 600 people were receiving medical treatment following Thursday afternoon's blast at the industrial park in Yancheng, said the city government on its official Twitter-like Weibo account. Among them, at least 90 were seriously injured.

The blast was so powerful it apparently triggered a small earthquake, knocked down several factory buildings and shattered the windows of homes a few miles away. It also created a crater, The Associated Press reports.

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A 60-year-old woman surnamed Xiang said, "We knew we'd be blown up one day." She said she had harbored concerns about safety and pollution at the site for a long time.

The AP said the plant's safety record is "dismal." It was cited last year alone for 13 types of safety hazards. And that happened even though the facility had been fined more than $267,000 since 2016 for breaking environmental regulations, the AP said.

Hundreds of rescuers were dispatched to the scene Friday, local authorities said, and more than 3,000 people were evacuated from the blast vicinity.

The official Xinhua News Agency reported that Chinese President Xi Jinping, who was on a state visit to Italy, demanded "all-out efforts" to locate and save victims.

More than 900 firefighters fought a blaze with raging flames that followed the explosion and managed to extinguish it after an all-night battle, local officials said. Three chemical tanks and five other areas were on fire.

Smoke billows from fire following an explosion at the plant owned by Tianjiayi Chemical, in Xiangshui county, Yancheng, Jiangsu province, China on March 21, 2019 CHINA STRINGER NETWORK / REUTERS

Authorities investigating the cause of the accident said an unspecified number of people were taken into police custody.

The chemical facility involved in the explosion belonged to Tianjiayi Chemical, a company with 195 employees established in 2007.

According to local officials, the Jiangsu-based company mainly produced raw chemical materials including anisole, a highly flammable compound.

The force of the explosion blew out windows and dented metal garage doors of buildings as far as 2-and-a-half miles from the site, said AFP reporters at the scene.

Nearby residents -- many of them elderly -- have started sweeping up glass, and in some cases, seemed to have abandoned their homes entirely. Black smoke could still be seen rising from the plant on Friday morning before dissipating.

On the road where Xiang lived, consisting of basic two-story homes, almost all the windows and some window frames were blown in.

The woman was sitting at home when the explosion occurred and said the force rocked her house and badly damaged her front door.

There was no immediate government help, she said, and residents were clearing the street themselves.

Images broadcast on local media showed how the blast toppled factory buildings, trapping workers inside. State broadcaster CCTV showed rescuers pulling a survivor from the wreckage.

Workers covered in blood were seen running out of the factory, said official news agency Xinhua on Thursday, citing witnesses.

An aerial view of the blast area showed a large swath of destruction in the industrial park, where multiple fires had initially raged.

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

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. A report published by local authorities last month revealed that the Chinese chemical firm responsible for that accident had concealed information and misled investigators.

In 2015, China saw one of its worst industrial accidents when giant chemical blasts in the northern port city of Tianjin killed at least 165 people. The explosions caused more than $1 billion in damage and sparked widespread anger at a perceived lack of transparency over the accident's causes and its environmental impact.