The NYPD cop who was killed in a hiking accident in Ulster County has been identified as Katarzyna Erario, a three-year member of the force from Manhattan’s 33rd Precinct in Washington Heights, a source said.

She was one of two city police officers killed in separate accidents Monday — including Royston Ferguson, who was struck while riding a motorcycle in Brooklyn.

Erario, 38, was hiking with a male friend in Minnewaska State Park Preserve on Monday when she fell about 50 feet through a hole in the ground – ending up in Sam’s Point Cave, a police source said. She was taken to Kingston Hospital in Kingston, where she died from her injuries.

Ferguson, 35, who worked in the Brooklyn North Precinct, was riding his motorcycle south on Rockaway Parkway in Canarsie at about 6:45 p.m. when he was struck by an SUV driven by a school safety agent who was making a U-turn on Rockaway Parkway, sources said.

He was taken to Brookdale Hospital, where he died.

The injured school safety agent was listed in stable condition at Kings County Hospital.

It did not appear that there was any criminality in the accident, and police said the investigation was ongoing.

The accidents came on an already dark day for the NYPD, as Officer Brian Moore died from injuries suffered Saturday when he was shot in the head by a street thug in Queens.