Photo taken on Aug 2, 2014 shows the workshop where a powerful blast happened in Kunshan, East China's Jiangsu province. [Photo/Xinhua] More photos

NANJING - An explosion has killed 69 people and injured more than 180 others after ripping through a factory in east China's Jiangsu Province on Saturday morning, government sources said.

The blast gutted a wheel hub polishing workshop owned by the Taiwanese-invested Kunshan Zhongrong Metal Products Co., Ltd in Kunshan City at 7:37 a.m., according to the city government.

There were more than 200 workers at the site when the explosion happened. Among the dead, 44 were immediately killed, while 24 died after medical treatment failed.

An initial probe indicated that the explosion might have been caused by flames igniting "dust" inside the workshop, officials said.

TRAGEDY

Video of the scene broadcast by CCTV showed thick black smoke rising from the factory when the explosion happened.

People ran out of the factory with blackened skin and their clothes in tatters.

A citizen near the factory said there was a huge sound, and "the door was blew open."

Photographs circulated on social networking sites showing charred bodies of victims on trucks or lying on the ground as black smoke billowed from the factory.

Xinhua reporters at the scene said the blast left two large holes in the factory's wall, with large equipment and pieces of broken glass scattered around.

Crowds looking for their relatives soon gathered outside of the factory. A citizen said he has been calling his wife's cell phone number since 8 a.m. but still couldn't reach her.

A staff member at the Kunshan Hospital of Traditional Chinese Medicine said most of the injured suffered burns to their body and respiratory system.

"Every 10 minutes, an ambulance carrying the injured arrived at our hospital. It's the weekend, so we're sort of understaffed and have had to call for backup," said the staff member, who asked for anonymity.

A local radio reporter told Xinhua that she saw an injured worker, whose clothes and hair were completely burned off and his body "as black as charcoal."

A total of 137 injured patients have been transferred to hospitals in nearby cities of Suzhou, Wuxi, Nantong and Shanghai, local officials said.

Doctors and nurses specializing in burns at Shanghai's Ruijin Hospital have arrived at Kunshan to help local hospitals, which are "crowded with injured patients," according to the hospital.

Local residents have been seen lining outside the city's blood banks, after the Kunshan branch of the Red Cross Society of China reported a blood shortage.

A group of family members were anxiously waiting outside the plant for news on their beloved ones. A woman told the China News Service that she lost contact with her husband, 45, an employee of the factory.

"Will you please help me check the casualty list to see if my husband's name is in it? But please do not put his name in your report. Our parents would be very worried if they happened to see that," she was quoted as saying.

Following the explosion, Chinese President Xi Jinping has ordered all-out efforts to treat the injured and comfort the families of the dead. He has demanded a full investigation into the accident and harsh punishments for those responsible.

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

COMPANY IN DOUBTS

Established in 1998, Kunshan Zhongrong mainly produces automobile parts. Its website said the company has 450 employees and listed General Motors as a client.

It is located in Kunshan's economic and technological development zone, which is 70 kilometers away from Shanghai. The largely industrial city of Kunshan and Jiangsu Province are home to many Taiwanese companies.

The blast has draped the company in doubts whether it had made enough precautions to protect its employees.

Officials have said the explosion was a work safety accident. Two senior executives of the company have been placed in police custody.

Chen Mengmeng, head of Jiangsu provincial environmental protection department said blast has not caused a "big impact" on the environment, but they had been conducting real-time monitors on air and water around the plant.

The blast followed a fire and explosion in a petrochemical company in Changzhou City, also in Jiangsu, on Thursday evening, which did not cause casualties.

LOOPHOLES

Dust explosions can occur when any combustible dust suspended in the air at a high concentration meet an ignition source. The dust explosion of Kunshan factory was not the first such case.

In August 5, 2012, a dust explosion in an aluminum lock polishing workshop in east China's Wenzhou City of Zhejiang Province killed 13 people and injured another 15.

In March 11, 2009, the residual of aluminum powder in an abandoned factory in Danyang City of Jiangsu Province exploded after subsidiary of China Railway Construction Corporation Limited rented the place for workers' housing. The accident killed 11 people and injured another 20.

To tackle the potential danger of aluminum and magnesium related productions, the State Production Safety Committee has launched a three and a half months campaign to straighten up regularities.

But the safety production rules were poorly enforced, according to a worker of Kunshan Zhongrong Metal Products Co., Ltd, who required anonymity.

"Checks are usual, but after the checks, no one's really following any safety rules," the worker said.

Some residents near the Kunshan factory expressed their concerns,"There are lots of factories around us, we are really afraid to be frank. The regulators come and go, but are they really doing their job?"