A South Korea cargo ship was investigated by China’s maritime authorities for “highly” suspected toxic chemical spill when it docked at Zhenjiang, Jiangsu Province, Xinhua reported.

The pollutants caused tap water in some parts of the city to emit a pungent smell, sending panicked residents to stockpile bottled water from supermarkets.

Reporters on Thursday were denied access to the suspected ship, now docked close to the city of Nantong. Local maritime officials were unavailable for comment.

The governments of Nantong and Zhenjiang both said water samples of the two cities on Feb. 4 did not detect excessive phenol. Meanwhile, the authorities have ensured residents that the supply of purified bottled water is sufficient.

Phenol, also known as carbolic acid, is an organic compound that can irritate eyes and skin. Soluble in water, if absorbed in large amounts it can damage the liver and kidneys.