Updated

SHANGHAI -- Carbolic acid spilled into a river that supplies drinking water to eastern China's scenic city of Hangzhou, knocking out supplies to more than half a million people in the suburbs and creating a run on bottled water in the city of 9 million.

A tanker truck carrying 20 tons of the caustic chemical overturned late Saturday night. The chemical, also known as phenol, was washed by rain into the Xin'an River about 150 kilometers (90 miles) southwest of Hangzhou, the city government said in a report on its website.

The city said an emergency worker died, but it did not say how. It said authorities temporarily shut down water plants and released extra water from nearby dams to dilute the spill, which affected the water supplies of at least 552,000 people in Hangzhou's suburbs.

The concentration of carbolic acid near the accident site remained at more than 900 times the safe drinking level as of late Monday, the report said.

Local officials did not immediately respond to phoned and written requests for comment.

Carbolic acid is an industrial chemical used to create plastic and other materials. Contact with it can cause burns and ingesting it can cause damage to internal organs and the nervous system. No details were available on the exact level of contaminant in the water supply.

Despite reassurances that drinking water in Hangzhou itself was safe, residents rushed to buy bottled water, leaving shelves in some supermarkets empty, the official Xinhua News Agency reported.

Hangzhou is famed for its scenic West Lake district, its tea plantations and for picturesque mountains that ring the city. City officials are said to be planning to apply for it to be designated a U.N. World Heritage site.

Hangzhou is also a major center for textile manufacturing and the capital of Zhejiang province, one of China's most affluent and industrial regions.

The spill follows recent news of lead poisoning of dozens of people caused by emissions from battery manufacturers based northeast of the city. That case came amid a widening crackdown on heavy metals pollution that resulted in shutdowns of hundreds of factories.