A blast ripped through a metal products factory in the eastern Jiangsu Province of China on Saturday morning, killing at least 68 workers and injuring 187 others, reports the New York Times. 

The explosion occurred at 7:37 a.m. in the city of Kunshan, where a number of factories that manufacture components for the thriving automotive industry are located. Many of the victims were young migrant workers who had just begun their day shift, which starts at 7 a.m. and ends at 11 p.m., according to news reports.

Forty victims died on the spot and others died on the way to the hospital. Many severely injured patients, some with burns covering 90 percent of their bodies, were transported to hospitals in nearby Shanghai, according to reports.

A Taiwanese-owned company, Zhongrong, owns the factory, and its customers include General Motors and other American companies, according to the company’s website.  The website states the company specializes in electroplating of aluminum alloy wheels, and prominently features the slogan “quality and safety.”

The Zhongrong plant explosion was caused by metallic dust accumulations that ignited as workers polished wheel rims in a workshop, according to initial news reports. Some plant employees had complained about poor ventilation and dust buildup in the polishing workshops, according to The Xinmin Evening News, a Shanghai newspaper.

The accumulation of combustible dust, a byproduct of sanding and polishing aluminum, steel and other metals, is a well-known industrial safety hazard.

The official Xinhua news agency said five factory supervisors were being questioned in what authorities described as an investigation into potential criminal negligence by the plant management.

In 2011, three workers died and 15 were injured when an explosion at a plant in Chengdu occurred. Investigators blamed the accident on aluminum dust accumulations in ventilation ducts at the plant, which made iPads for Apple.

Tens of thousands of factories drive the vitality of the Chinese export sector. The Kunshan explosion is the most recent in a string of accidents that have focused attention on factory safety records.

About 70,000 lives are lost annually due to industrial accidents, according to figures released last year, although in recent years the Chinese government has increased enforcement of occupational safety standards.