This family were in for a shock when they visited the monkeys at Silver Springs State Park, Florida, recently.
The rhesus monkeys first watched the visitors warily but then started getting closer.
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The person behind the camera can then be heard screeching: "The monkeys are attacking!"
The family members wisely decided this was the right moment to make a hasty exit and luckily they weren't hurt during the surreal experience.
It looks like they hadn't spotted the flyers warning visitors to keep their distance from the animals.