At least five Manhattan schools were sent packages with mysterious white powder inside in the past week, police said Thursday.

Each of the schools received a white envelope with the address handwritten in block letters that contained the suspicious substance, later found to be harmless, according to the NYPD.

“It appears that the motive of the sender is to cause disruption and alarm,” cops said in a statement.

One of the incidents happened Tuesday morning at River Park Nursery School on the Upper West Side, Patch reported.

All 19 children and four staffers inside the building on Amsterdam Avenue near 95th Street were evacuated.

Cops didn’t provide any information on a possible suspect.

People who receive suspicious mail should not handle the packages and should immediately call 911 instead, the NYPD warned.