Ten workers died of smoke inhalation while renovating a pipeline at a pharmaceutical factory on Monday afternoon in east China's Shandong Province.

Building of Qilu Tianhe Pharmaceutical (File photo: official website of Qilu Tianhe Pharmaceutical)

The work safety watchdog in Jinan, capital city of Shandong, received a report of an accident in the factory of Qilu Tianhe Pharmaceutical. Preliminary investigation found the fumes were caused by burning combustibles that were ignited by welding sparks.

Eight workers were killed at the renovation site and two were declared dead at a hospital. The accident also injured 12 rescuers, but none of them was in life-threatening condition, said local authorities. 

The harmful smoke did not contaminate the surrounding environment, said the local environment agency, and an investigation is underway.