NEW YORK (CBSNewYork) — The NYPD is investigating another suspicious substance that was mailed to a New York City preschool.

CBS2 has been told white powder was found Friday in a letter addressed to the River Park Nursery School on Amsterdam Avenue on the Upper West Side.

The school also received a letter with white powder on Tuesday.

The NYPD says a total of five schools have been targeted over the past eight days. They say envelopes sent to the schools have all contained a powder determined to be non-hazardous.

Investigators say it appears the motive is to cause disruption and alarm.

MORE NEWS: Suspicious Packages Containing White Powdery Substance Mailed To 5 Manhattan Schools

So far, no arrests have been made.

CBSNewYork Team