It sounds like the plot to a bad B-movie.

Meat-eating killer frogs have invaded a pond in San Francisco's Golden Gate Park, leaving environmentalists wondering how to stop their deadly march before they move on to bigger waters.

The African clawed frogs have chomped through everything from turtles to fish in Lily Pond, near the California Academy of Sciences, the San Francisco Chronicle reported.

• Click here to read the San Francisco Chronicle story.

The frogs, which can grow up to 5 inches in length, have even gone cannibalistic.

"They've eaten everything they can get their mouths around, and now they're eating each other," Eric Mills of the animal-rights group Action for Animals told the newspaper.

Park officials have pulled some 2,500 of the frogs from the pond since 2003. They are taken to a fish and game facility where they are euthanized by a nerve poison, the paper said.

But the frogs keep coming back. Last week, the city's Animal Control and Welfare Commission voted to ask the city for cash to drain the pond and terminate the population once and for all, the paper reported.

"The fear is they will get out," Richard Schulke, president of the city's Animal Control and Welfare Commission, told the paper.

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