A gas pipeline leak on Monday has killed seven workers in north China's Hebei Province, said local authorities Tuesday.

A total of 16 workers were poisoned while assembling a furnace at 11:45 a.m. Monday in Hebei Puyang Iron and Steel Co., Ltd., said Li Shuming, general secretary of Wu'an municipal government, Hebei.

Seven were confirmed dead and the other nine were in stable condition, Li said.

The pipeline that the gas leaked from belongs to Puyang company, and was constructed by Nanjing Sanye utility installment company, according to Li.

The company that the poisoned workers are from is still unknown.