Boston Police are searching for a man identified as a person of interest in an armed robbery investigation, the department said Thursday.

Ongoing incidents of pedestrians being robbed with a 12-inch kitchen knife have been reported downtown, police said in a blog post.

The department posted two pictures of a man to its site on Thursday.

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Last spotted around Washington and Boylston streets, he is described as a man standing 5 feet 7 inches tall with “missing teeth,” police said.

The department generally refers to a suspect as a "person of interest," rather than a "suspect," when police do not know an individual's name, a spokesman told Metro.

Police urged anyone with information to contact the Boston Regional Intelligence Center at 617-343-4328, the anonymous CrimeStoppers Tip Line at 1-800-494-TIPS or the anonymous text-a-tip line at CRIME (27463).