The incident occurred around 1:11 p.m. at the park, said Dan Keefe, spokesman for the park police.
The officer was not injured and all park visitors were safe, officials said.
Keefe said park police were not releasing additional information regarding the incident.
Harriman is New York's second-largest state park. Located 30 miles north of New York City in both Orange and Rockland counties, it encompasses 47,527 acres.
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