Vanessa Trump, the wife of the eldest son of US President Donald Trump had to be rushed to the hospital on Monday due to symptoms of nausea after opening mail containing an unidentified white powder, which was later found to be non-hazardous.
"The substance was deemed to be nonhazardous and is being transported to a lab in New York City for further analysis", NYPD Assistant Commissioner J. Peter Donald said.
Later Trump Jr. also tweeted about the envelope and said that he was thankful that his wife and kids were safe.
The President's daughter Ivanka Trump, also weighed in. No one deserves to be frightened this way. There is no excuse.
Detectives from the New York Police Department's intelligence division and Secret Service agents are investigating.
The US Secret service is investigating. The two got married in 2005 at Mar-a-Lago in Florida.
'Unbreakable Kimmy Schmidt' Season 4 to release in two parts
The first six episodes of the new season will be released on May 30 with the second half of the season to premiere later in 2018. Take a look back at Unbreakable Kimmy Schmidt's third season in the video below.
White House spokeswoman Sarah Huckabee Sanders said at her press briefing: "I know the president spoke with her (Vanessa)".
In 2001, several envelopes mailed to newsrooms contained anthrax, and five people died after being exposed.
The investigation into the letter Monday was being led by the New York Joint Terrorism Task Force - not because investigators believed it was an act of terrorism, but because the task force tends to take the lead on white powder threats.
Mrs Trump previously worked as a fashion model in NY and is a former Miss USA contestant.
Trump Jr. has been in the public eye for his role in a 2016 meeting in Trump Tower with a Russian attorney and others after the Trump campaign was offered potentially damaging information about Democratic rival Hillary Clinton.
Donald Trump Jr, an outspoken defender of his father and who was the intended recipient of the letter, called the incident "truly disgusting".