Doctors and nurses at Shanghai No.3 People's Hospital treat severely injured workers after an accident at a Baosteel plant in Baoshan district Monday morning. At least two workers died and 13 were injured when a ladle of molten metal tipped over. Photo: Cai Xianmin/GT

Two workers died and another 13 were injured Monday after a 270-ton ladle of molten metal tipped over at a Shanghai Baosteel Group Corp plant in Baoshan district.

The accident happened around 9:10 am when the ladle toppled from its hooks at the plant, according to the local news website Xinmin.cn.

The overturned molten metal, which had been heated to 1,600 C, killed two of the workers instantly, Shanghai Television Station reported.

"The workers were removing slag from the molten metal when the accident occurred. The injured workers were sent to Shanghai No.3 People's Hospital," Baosteel said on its official microblog.

Baosteel is one of China's largest steel companies.

The 13 injured workers arrived at the hospital around 10 am, said Qin Yan, a spokeswoman at the hospital. "Six of them are in critical condition. They have burns over large areas of their bodies and have suffered inhalation injuries," Qin told the Global Times Monday afternoon. "The other patients have been stabilized."

Five of the workers had been upgraded to stable condition, the Shanghai Administration of Work Safety said on its microblog Monday night.

Two of the workers were transferred to the Burn and Trauma Department at Changhai Hospital.

The great amount of searing steam burned the patients, who would have die from inhalation injuries if they weren't treated, said Lü Kaiyang, an attending physician in the department.

"The patients need to stay in the intensive care unit for 24 to 48 hours for further monitoring," Lü told Shanghai TV.

The most seriously wounded patient has burns over 99 percent of his or her body, according to Xinmin.cn. The other five have burns over 20 percent to 50 percent of their bodies.

Deslagging is a steelmaking process in which the metal is purified, said Yang Yitao, deputy director of the Department of Materials Engineering at Shanghai University. In this process, workers scatter an agent on the surface of molten metal to absorb impurities, which solidify so workers can manually remove them.

"The workers must approach the ladle to do it," Yang told the Global Times. "There is a certain risk to the work, but it isn't high."

The ladle can tip over if it isn't hung tight enough or if the lifting machinery is too old, Yang said.

The Shanghai Administration of Work Safety has created a team to investigate the accident, according to a post on its official microblog. The team will include personnel from local police, the prosecutor's office and the district government.