The robber, dressed in dark clothing, handed a note to the teller demanding money at the Investors Savings Bank at the corner of 4th Street and Clifton Avenue just before 3 p.m., Sgt. Robert Anderson said.
He "implied that he was armed, but no weapon was shown," Anderson said.
Clifton police were investigating with assistance from the FBI-Newark Field Office, he said.
The Passaic County Sheriff's Office responded with K9 and Crime Scene Investigation units.
Anyone who saw something or who has information that can help catch the robber is asked to contact the Clifton Police Detective Division: (973) 470-5908.
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