More than 100 fish have been killed in a suspected pollution incident in a river in Cornwall.
The fish, and large numbers of dead insects and beetles, were found on the river which runs between Barippa and Penponds, near Camborne.
The Environment Agency said a 6km (3.7 mile) stretch was affected in what it described as a "significant incident".
It added that it was unsure where any pollution had come from but added that its investigations were continuing.
Mark Pilcher of the agency said staff "won't rest until we find out what's caused it".
He said: "We think at this stage the event is something that has passed through the river and has been flushed out.
"Our feeling is that it was pollution that came through, perhaps with heavy rain that we had recently, and is now gone.
"Hopefully the river will recover, but it will take a while."
He added: "People should not pick up any dead fish they find - they've died for a reason we're not fully aware of."
He added that animals should also be kept away from the river and that if anyone felt ill after being close to the river, they should contact Cornwall Council's Environmental Health Department.