An ammonia leak sickened 20 people in central China on Friday, including five with severe symptoms, local officials said. No deaths were reported.

Authorities in Pingdingshan city said in a statement that about 300 kilograms (660 pounds) of ammonia leaked for 15 minutes after a pipeline at a local coal plant ruptured, sickening villagers near the factory.

Photos by local media show a white fog-like gas shrouding what appears to be a factory area. Local authorities said the plant was able to halt the leak and no ammonia was detected in the air about three hours after the rupture.

Workplace safety hazards abound in China. In August, a warehouse storing hazardous chemicals caught fire and exploded in the northern port city of Tianjin, killing 165 and leaving eight missing.

In 2013, a gas line ruptured in the eastern port city of Qingdao, triggering blasts that killed 62 people.