The monkey, named Eujo, somehow got out of its cage and hurt one of the boys at the home where it lived.
When deputies arrived, Eujo's owners had barricaded themselves in the home for protection.
They say they never saw the attack coming.
"I woke up to my brother's friends yelling 'monkey' and running," said attack victim Skyler Phelan.
"I've never seen any animal jump on top of somebody for no reason and start attacking them," said friend Caleb Galloway.
The animal was recaptured and is now back in its cage. However, there is no word on how it escaped.
The victim is expected to be okay.