President Donald Trump's daughter-in-law opened a letter containing an unknown substance that was addressed to the President's son Donald Trump Jr., the New York Police Department said.
The letter was sent to the couple's Manhattan apartment and opened around 10 a.m. ET Monday, authorities said. Vanessa Trump did not have an immediate reaction to the substance, which the NYPD said was deemed nonhazardous.
The Fire Department of New York said three people were transported to a local hospital with minor injuries, but did not provide additional information on the nature of the injuries or the victims.
The Secret Service acknowledged that it was participating in the investigation but declined further comment.
Check back for updates on this developing story.