Police have urged calm after a reported sighting of panther-like big cats near Barrow in Cumbria.
Two animals were spotted crossing a road near Jubilee Bridge, which takes traffic onto Walney Island on Tuesday.
An eyewitness described the animals as "large, black and panther-like."
A Cumbria Police spokesman said although there were no other sightings, the public should be aware of possible dangers of approaching wild animals.
Betty Sloane, who reported the animals to the police, said she is convinced they were not domestic animals.
She said: "I have been born and bred in the country and I know animals that run around locally.
"This was just such a strange thing that I had never seen before.
"I am absolutely sure these were panther-like cats. They crossed over the bridge straight in front of me.
"At first I thought they were big foxes and they way they lunged over you could tell they weren't dogs."
A spokesman for Cumbria police said this was the first sighting of big cats in the Barrow area.
He said: "I would advise people to keep a discreet distance should they see anything similar.
"If these animals are out there they will pretty much keep themselves to themselves.
"There is only danger if you get too close or approach them when they have young.
"We would advise people to keep their distance and contact the police if there are any further sightings and we will take it from there."
The British Big Cats Society said the number of big cat animal kills and sightings around the country was growing steadily.
But the Department of Environment, Food and Rural Affairs (Defra) says there is no proof that big cats are roaming the British countryside.