Threatening letter reportedly sent to Eric Trump
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Authorities are investigating a threatening letter sent to Republican presidential candidate Donald TrumpDonald John TrumpSarah Huckabee Sanders becomes Fox News contributor The US-Iranian scuffle over a ship is a sideshow to events in the Gulf South Korea: US, North Korea to resume nuclear talks 'soon' MORE's son Eric that contained a suspicious white powder, according to reports.
The mail was opened by Eric Trump's wife on Thursday, according to CBS News, which reported that a source said it had a Massachusetts postmark. The letter warned that if Donald Trump did not withdraw from the Republican presidential race, his children would be harmed. 
The letter was sent to Eric Trump's Manhattan residence at Trump Parc East. A law enforcement official said it contained a suspicious white powder.
New York City police and the FBI are investigating the incident.
A preliminary field test of the substance indicated it did not appear to be hazardous, according to reports. No injuries were reported.
Eric Trump, 32, is the third-oldest of Donald Trump's five children.