One man was killed and another was critically injured Tuesday morning in an explosion at a Baosteel factory in suburban Baoshan district.

The fatal accident occurred at 10:20 am near a cafeteria in Shanghai Baosteel Group Corp's Tieli community when  a truck used to collect waste heat exploded, shattering the windows of nearby buildings, said Meng Haibiao, spokesperson for Baosteel Group.

"I heard a loud bang outside my office on the third floor," a witness surnamed Ye told the Global Times. "When I looked out of the window, I could only see smoke - nothing else. Many people rushed out of the cafeteria to call for help."

The two victims, both natives of Shandong Province, were not Baosteel employees, but worked for the Shandong-based Zhongyineng Energy Corp, which Baosteel hired to collect waste heat at some of its facilities, Meng said.

The two workers were the ones standing closest to the truck when it exploded. They were rushed to the nearby Shanghai No. 3 People's Hospital, also known as "Baosteel Hospital," where one died while doctors were treating his burns. He was pronounced dead just before 1 pm.

The other worker suffered burns over 85 percent of his body and remained in critical condition Tuesday afternoon, said Fang Yong, a burn specialist at the hospital. "Doctors were trying to stabilize his condition, but the burns were very severe," he told the Global Times. "We are not sure if he will pull through."

Although the victims were not Baosteel employees, the company will provide financial assistance to the victims and their families. "It was a very unfortunate accident and we have already contacted the workers' employer and their families," Meng said. "We will offer to help the victims' families cover their medical and funeral expenses."

Huang Lanlan contributed to this story