NEW YORK -- The Hillary Clinton campaign says four people have been examined by medical personnel after a white powdery substance arrived at a New York campaign office and they have reported no health issues.

Campaign spokesman Glen Caplin said in a statement to CBS News that federal and local officials determined the substance was non-hazardous; he provided no further details Saturday.

Police say preliminary tests showed the substance found Friday in an envelope at Clinton’s Manhattan office, where mail is received, was not harmful. A police spokesman declined to identify what the substance was.

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The envelope arrived around 5:30 p.m. Friday. It was taken to Clinton’s Brooklyn headquarters.

“Our office remained open throughout this period and will remain open without interruption” on Saturday, Caplin said.