Residents of the northeastern Chinese city of Harbin have been flocking to leave the city after officials there turned off the city's water supply for a second day Wednesday.

Authorities shut off Harbin's water after an explosion at a nearby chemical plant on November 13. China's environmental protection agency on Wednesday confirmed that extremely dangerous amounts of toxic benzene had spilled into the Songhua River, which supplies the city of nearly four million people.

Officials said it would take at least four days to restore the public water supply.

Residents who could afford it flocked to leave the city. Airline representatives told VOA all flights out of Harbin were sold out late Wednesday, and witnesses said trains leaving Harbin were full.

Schools in the city were closed Wednesday, and officials said hospitals were using reserves from water tanks.

This Harbin resident says that after learning that tap water would be shut off, people in the city rushed to stock up on bottled water, and do whatever they could to get them through the next few days.

"They have bottled water, and they just filled every container in their home in preparation," he said. "There was a shortage in the shops. It was very hard to get bottled water or purified water in some places."

Benzene is a common gasoline additive that can be deadly if breathed or ingested in high concentrations. Officials on Wednesday said the levels of the substance found after the blast last week were 108 times above what the Chinese government considers safe.

The Songhua is the largest tributary of the Amur River, which flows along China's border with Russia. Chinese Foreign Ministry spokesman Liu Jianchao this week sought to reassure Moscow that it is taking measures to prevent cross-border contamination.

Mr. Liu said China will take measures in the interests of its neighbors.

As China's economy continues to boom, its industries have been developing quickly - often at the cost of the environment, and often outpacing the growth of the country's infrastructure. Observers outside China said the incident in Harbin this week highlights a need for improved pollution controls and emergency preparedness.