The Zouping County government says on its official microblog the leak occurred late Saturday and poisoned 17 people, five of whom died immediately. It says five more died early Sunday, and the cause of the leak is under investigation.
Satellite images show the factory next to warehouses and low-rise residential homes in a village about 60 kilometers (40 miles) east of Jinan, the Shandong provincial capital.
The deadly leak is the latest industrial accident in China, where authorities are under pressure to improve work safety after a huge chemical blast in Tianjin killed at least 140 people and left a swath of the port city in smoldering ruins.
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