Flooding in the northeastern Chinese city of Jilin have washed thousands of containers of explosive chemicals into the Songhua River.
Water supplies have been cut and emergency teams have been sent to recover the spilled fluid. They were washed away when flood waters ran through two large chemical storage facilities.
Jilin suffered a similar spill in 2005 when a petrochemical plant released dangerous pollutants into the river.
Environmental protection authorities say they have so far detected no contamination from this latest incident.
China has been hit by its worst seasonal rains in a decade that have killed 333 people and left another 300 missing.