The Shanghai municipal government announced on Sunday that loose fittings on pipes caused the fatal liquid ammonia leak at a cold storage plant in Shanghai's Baoshan district, which has caused 15 deaths.
Twenty-five injured people, including several that were seriously injured in earlier reports, are now in stable condition, the Shanghai government said in a statement late on Sunday.
Most of the injured suffered burns. Those who died suffered serious facial burns, making it difficult to identify them, according to a report on the local news portal eastday.com.
The accident happened at around 10:50 am at Shanghai Weng's Cold Storage Co., a company specializing in frozen food processing, transportation and storage.
"I heard a loud bang and then saw thick white gas. The odor irritated my nose," Yin Yuqin, an injured 42-year-old worker, who is receiving treatment in Shanghai No.3 People's Hospital, told Shanghai Television.
The authorities said it will conduct a citywide inspection on plants that use liquid ammonia to prevent accidents in the future.
Liquid ammonia is used as a low cost refrigeration agent at many cold storage plants, said Cen Jianrong, manager of Shanghai Wusong Luoji Cold Storage Co., another frozen food plant in Baoshan district.
It can be dangerous when it leaks, as it can suffocate and cause serious internal and external burns, and it may cause explosion if it catches fire, Cen said.
A report in the Beijing Times quoted Weng's workers as saying that they were never given safety training on ammonia.
Accidents caused by ammonia leaks are not unusual.
One leak caused an explosion at a poultry company in