Environmental authorities in northeastern China are monitoring chemical levels in a major river after floodwaters carried more than 3,000 barrels filled with toxic chemicals into it.

State-run Xinhua news agency says the containers floated into the Songhua River in northeastern Jilin province Wednesday after flood waters swept through a chemical plant.  Another 4,000 barrels that washed out of the factory were empty.

Officials briefly cut off water to Jilin city, leaving its four million citizens dependent on bottled water for a day.

The city's environmental authority says it has only collected 400 of the floating barrels so far. But officials say they have detected no contamination of the Songhua River.  

An explosion at a benzene factory in 2005 led to a chemical spill in the Songhua, leaving millions of residents without drinking water for four days.

Flooding in China this year has killed almost 900 people and left more than 400 missing.  The flooding is the worst in more than a decade and has caused billions of dollars in damage.

About 30,000 people in the town of Koquian in Jilin province were trapped due to torrential rains that caused the Xingshan Reservoir and the Wende and Songhua rivers to overflow Wednesday.

Some information for this report was provided by AP, AFP and Reuters.