The Trump family is on high alert after Donald Trump Jr.'s wife, Vanessa, was exposed to a "white powder" at her home.

According to police, Vanessa Trump was at the family's Manhattan apartment when she opened a letter addressed to her husband. A white powder was inside the envelope, which prompted immediate concern. Mrs. Trump called 911, telling dispatchers she was "coughing and felt nauseous."

Both the New York Police Department's intelligence department and Secret Service agents were investigating the incident.

"The Secret Service and our law enforcement partners in New York City are investigating a suspicious package addressed to one of our protectees received today in New York, New York. This is an active investigation and we cannot comment any further," Secret Service Special Agent Jeffrey Adams said in a statement.

Both Vanessa Trump and two other unidentified individuals were decontaminated by firefighters at the scene. Vanessa was taken to hospital as a precaution.

After extensive testing, it was confirmed that the substance was non-hazardous. However, more testing will be conducted at a lab in New York City to identify what exactly it was. Vanessa and Donald Jr. share five children together, none of whom were at home at the time of the incident.

This is not the first time the Trumps have been sent mysterious powders, either. In March of 2016, Eric Trump was mailed an envelope with white powder that was later found to be harmless. That same year, envelopes containing white powder were sent to Trump Tower, which was serving as Trump's campaign headquarters.

Police are still investigating the incident, trying to track down who sent the powder.