Foul play has been ruled out after three dogs died and another seven became ill after drinking water from a lake in Kent.
A spokesman for Kent Police said there was nothing to suggest that "foul play or anything sinister" had taken place at Brooklands Lake, Dartford.
In a statement, the force added that "no criminal offences have been disclosed".
An investigation will continue, though, conducted by Dartford Council and the Environment Agency (EA), amid fears of contamination.
Officers set up a cordon and warned locals to stay away after a dog walker reported that three of her animals had become ill and died on Tuesday.
A spokesman said: "It is believed they (the dogs) got into the lake and drank from it. They came out and started fitting.
"Shortly after that three of them died ... "
Parkvets Veterinary Hospital in Footscray, Sidcup, said it knew of 10 dogs that had been affected, including the three which had died, while the surviving animals were being kept under observation.
Dartford Council, which owns the land at the site, said: "We are waiting for the results of water tests from the EA and also any toxicology reports we get back from the vets as to what the possible cause is."
The council has asked people to take notice of warning signs and not allow their dogs to enter the water.
The RSPCA advised people who were concerned that their pet may have been poisoned to contact a vet immediately.