According to NBC News, the letter said: “You are an awful, awful person. I am surprised that your father lets you speak on TV. You the family idiot. Eric looks smart.”
“This is the reason why people hate you,” the note continued. “You are getting what you deserve. So shut the f— up.”
President Trump’s son took to Twitter Monday afternoon to confirm that his wife, Vanessa, and five young children were “safe and unharmed” after the family received a letter containing a white, powdery substance earlier in the day.
“Truly disgusting that certain individuals choose to express their opposing views with such disturbing behavior,” Trump Jr. added in the tweet.
A spokeswoman for the NYPD’s office of the Deputy Commissioner of Public Information told PEOPLE that the suspicious substance was tested and proven to be non-hazardous.
The spokeswoman confirmed that three people were taken to a local hospital for observation after the incident but could not confirm their names.
NBC News reported Monday that Trump Jr.’s wife was taken to New York Presbyterian-Weill Cornell Medical Center “strictly as a precaution.”
The Secret Service is also investigating the incident, NBC News said Tuesday.
The letter was sent to Trump Jr.’s mother-in-law’s home in New York, according to the New York Post, which also reported that the suspicious substance in the letter was cornstarch.