Medics transfer a badly burned victim of the blast in a car parts factory from Kunshan to Shanghai Saturday afternoon. Many of those injured in the explosion on Saturday morning have been transferred to other hospitals in Jiangsu Province and Shanghai for better medical treatment. Photo: Yang Hui/GT

 The death toll from a blast at a car parts factory climbed to 71 Sunday, as concerns mounted over safety at the plant.

Police detained five officials in the wake of the explosion, in which 186 employees were injured, many severely. Desperate relatives on Sunday continued to hunt for their loved ones. 

The blast, at 7:37 am Saturday, occurred in the wheel hub polishing workshop of Taiwanese-invested Zhongrong Metal Products Co.

There were 264 people in the workshop at the time. Zhongrong supplies car manufacturer including US car giant General Motors and other US auto makers, according to its website.

Officials from Kunshan, around 50 kilometers from Shanghai, said the blast was due to lax safety and probably caused by a naked flame in a dust-filled room.

Kunshan mayor Lu Jun said on Saturday that five people from the factory were detained by police and further measures will be taken after the results of an investigation by the State Council investigation group are released. 

President Xi Jinping sent a team headed by Wang Yong, one of China's five State councilors, to oversee rescue work and investigate the accident, the Xinhua News Agency reported.

Many of the 186 injured were transported to 15 hospitals in eight cities nearby in Jiangsu Province and in Shanghai. Many victims sustained severe burns, some to 100 percent of their bodies.

Ten were sent to Changhai Hospital in Shanghai and all were admitted to the intensive burns unit. Zhu Shihui, deputy director of the unit, said that patients had suffered extensive burns and inhalation injuries. None had blast injuries.

The factory employs 450 workers in its seven workshops. Questions have been asked as to why so many people were working on a Saturday.

One of the victims, surnamed Cui, came from Gansu Province and had worked at Zhongrong for four years. Her husband, surnamed Gao, told the Global Times she has suffered 95 percent burns.

"Her basic salary is 1,530 yuan ($247) a month. She has to work weekends to earn extra and stay late to complete work," Gao said. He said that his wife started her shift at 7 am and did not finish until 11 pm.

"The working environment in the workshop was also very bad. When she got home after work, her face and hair were covered with dust," he said.

Another man called Qiao Biao said that he and his father had looked in vain for his mother, Zhao Jianhua, who had not been seen since Saturday morning.

They had searched all the nearby hospitals in Kunshan and Suzhou, but had not managed to find Zhao.

Many of the identities of the dead and injured have not been confirmed due to the severe nature of the injuries.

Staff from Kunshan public security bureau said Sunday they started to collect DNA data from relatives of the dead and injured to identify the casualties.

Zhong Shengjun, an associate professor at the Industrial Explosion and Protection Institute of Northeastern University in Changchun, Jilin Province told the Global Times that such an explosion could be avoided and the factory's dust removal system was probably at fault.

China has a poor record with industrial safety. According to the State Administration of Work Safety, there have already been 644 "large accidents" from January to July this year, killing 2,695. 

Premier Li Keqiang has ordered safety checks to avoid similar tragedies from happening again, Xinhua reported.

The safety supervision bureau of Kunshan ordered several local companies, including Taiwan-owned Foxconn to suspend production for safety checks.

Production will only be reinstated after these factories pass official inspection, China News Service reported Sunday.

Major blasts involving industrial powder

On February 24, 2010, an explosion at a corn powder workshop at Qinhuangdao Lihua Starch Co in Qinhuangdao, Hebei Province left 20 dead and injured 48.

On May 20, 2011, blasts occurred at a branch of Foxconn Technology Group in Chengdu, Sichuan Province, killing 3 and injuring 15. The workshop was polishing Apple iPad 2 parts.

On August 5, 2012, an explosion involving aluminium powder at a home workshop in Wenzhou, Zhejiang Province, caused a fire and the collapse of an apartment building, which killed 13 and injured 15.

On April 16, 2014, stearic acid powder manufacturer Shuangma Chemical in Ruhao, Jiangsu Province saw a blast in one of its workshops, which killed eight and injured nine.