Visitors reported that the grisly scene began as several bears chased the monkey, a macaque, onto a wooden structure at Beekse Bergen Safari Park.
They said a bear tried unsuccessfully to shake the monkey loose, ignoring attempts by keepers to distract it. The bear then climbed up and grabbed the monkey, mauling it to death and bringing it to its concrete den, where three bears ate it.
The park confirmed the killing. "The habitats here in the safari park are arranged in such a way that one animal almost never kills another, but they are and remain wild animals," it said in a statement.
The attack occurred in an area of the zoo that contains both monkeys and sloth bears, a type of black bear found in the Asian subcontinent.
The park said it plans now to move the macaques to another part of the park.