China ? China’s government defended its handling of a chemical plant explosion that sent a 50-mile-long toxic slick of river water coursing through a major city Thursday.

The benzene slick on the Songhua River in northeast China flowed into Harbin days after the city of 3.8 million people shut down its water system. The government said it would take about 40 hours for the chemical to pass the city.

A government official said local leaders were warned of the chemical threat after the Nov. 13 blast that killed five people, and no one was sickened.

“It was handled properly,” said Zhang Lijun, deputy director of the State Environmental Protection Administration.

The government did not publicly confirm the Songhua had been poisoned until Wednesday.