OREANDA-NEWS. Five educational institutions in Manhattan, including kindergartens and preschools, received letters with a «white powdery substance» in the last seven days, the «Wall Street Journal» newspaper reports, citing the New York police.

According to law enforcement officers, two of the five envelopes were received on Thursday, and no arrests have been made yet. It is noted, that the unknown person sent letters through the US postal service in the period from 10 to 18 March, the addresses of the establishments were written on the envelopes by hand in block letters.

Despite the fact, that the substance in the envelopes did not pose a danger, the police believe, that the sender intended to cause a stir. New York City Mayor Bill de Blasio has warned, that the sender will be held accountable.

«We must remain vigilant and ensure the safety of all students and staff in our schools, but we must not give this scoundrel what he wants — to sow fear and panic», de Blasio said.

Earlier this week, it was reported, that one of the kindergartens in Manhattan was evacuated after a package with a «white substance» was delivered there. The package was not dangerous and the substance was transferred for examination to the Department of Health of New York.