Police said the cabbie picked up three men on Sunday, Feb. 28, in the hamlet.
Shortly afterwards, one of the suspects pulled a knife and demanded money, they said.
Police, who did not disclose the amount of cash the robbers got, said the three then fled on foot.
Police are asking anyone with information about the case to call them at (845)-357-2400.
Police also said they investigated five motor vehicle accidents on Sunday. Their locations were: Cloverdale Lane and West Central Avenue in Monsey; Route 17 in Hillburn; Cherry Lane in Airmont; and Route 202 in Pomona.
They also responded to 120 calls for service, including six arrests, two for driving while intoxicated.
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