New York City police likewise say preliminary tests showed no threat from white powder that was found in a letter sent to former New York City Mayor Rudolph Giuliani's company in Manhattan.
In New Jersey, the suspicious mailings went to at least five hotels, Carlstadt Police Detective John Cleary said.
The federal law enforcement official, who wasn't authorized to comment publicly and spoke on condition of anonymity, said powder from one envelope tested positive for baking soda. It's not clear where that letter was sent.
Hackensack University Medical Center received a number of people for evaluation because they came in contact with the letters, but a hospital spokeswoman said there were no reported illnesses or injuries.
The mailings arrived at an Econo Lodge in Carlstadt, a Homestead Inn in East Rutherford and a Renaissance Inn in Rutherford, Cleary said. Investigators intercepted additional envelopes from a mail truck before they reached a Holiday Inn Express and Hampton Inn in Carlstadt, he said.
Police were called to Giuliani's consulting firm near Rockefeller Center after a worker opened the suspicious letter addressed to Giuliani around 10:30 a.m. Friday, police said. Eight mailroom workers underwent decontamination as a precaution.
A representative for Giuliani's firm did not immediately respond to a comment request.
Associated Press writer Alicia A. Caldwell in Washington contributed to this report.
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