Footage shows a huge colony of 'swamp rats' which have invaded a park in Texas, as you can see below:
The creatures could easily be mistaken for huge rats, but are actually a type of beaver called a nutria.
As you can see from the video, the rodents have yellow teeth and long rat-like tails and wardens at the Krauss Baker Park in Fort Worth are urging people not to encourage the growth of the colony.
The rodents can eat up to a quarter of their body weight in a day and big settlements can mean the water quality could decrease, leading to potential outbreaks of infections in the area.
Female nutrias can have up to 200 offspring a year, meaning it's easy for colonies to get out of control.
Confused locals shared photos and videos of the unsettling creatures congregating in the local park.
Rachel Richter, a wildlife biologist for Texas Parks and Wildlife, told WFAA: "If not controlled, you end up with erosion, destabilized banks, decreased water quality, and a lot less of a habitat for native plants, animals, and fish."
And they can be harmful to people because of the parasites the bring to the water.
She added: "They are harmful to humans because they degrade water quality in water bodies that might be used for recreation or drinking water.
"They are also vectors for pathogens and parasites that could contaminate a water body and potentially infect people."
Richter believes that about 20 of the creatures are being well-fed by park rangers and well-meaning members of the public, but urges them to stop.
She explained: "Feeding wildlife is really something that you shouldn't do under any circumstances.
"It can cause the populations to artificially inflate, which can damage the ecosystem. When people feed wildlife, they normally have the best intentions. But they don't realize that they could be doing harm."
Authorities in Fort Worth say they are monitoring the situation but it's not just a problem in Texas.
Originally taken to the US in the 1800s, nutrias were sold as vegetation control because of their huge appetites, but they have since become a 'nuisance'.
In the state of Louisiana it's said that there are an estimated five million nutrias, compared with a human population of 4.6 million.
In Louisiana, hunters are employed to attempt to keep the population under control.