Tons of deadly cyanide leaked into a river in central China after a lorry carrying it overturned.
Animals were poisoned and at least one person fell sick from water contamination.
The lorry carrying 11 tons of liquid sodium cyanide overturned on Thursday on a rutted road along a tributary of the Luohe River in Luoning, in Henan province about 500 miles southwest of Beijing, a local official said.
A pair of dams were erected to try to contain the spill, but one man fell ill after eating sweet potatoes washed in contaminated water. He was said to be recovering.
The lorry driver, who fled the scene, was later arrested along with a representative from a gold mine that bought the cyanide and four other men.
Mines use cyanide to extract metals from ore.
The Luohe river provides drinking water for the industrial city of Luoyang, but it had not been contaminated, said an official.
Police and soldiers poured tons of bleach and calx, similar to lime, into the river to soak up the spill.
The official China Daily newspaper said livestock were killed by the contamination but gave no details. Contamination was claimed to have affected only a few miles of river between the two containment dams.