Donald Trump Jr

Federal authorities are investigating who sent an envelope containing a suspicious white powder to the daughter-in-law of President Donald Trump.

The envelope was addressed to Donald Trump, Jr., but his wife Vanessa Trump opened the envelope inside her Manhattan apartment on Monday morning. Vanessa panicked and called 911 when a white powder spilled out of the envelope.

Fearing the powder was Anthrax — which is fatal if inhaled — everyone inside the apartment was rushed to a hospital and a hazmat team was dispatched to the apartment to collect the powder.

But the Anthrax scare turned out to be a hoax.

Law enforcement sources told the New York Post that the powdery substance was cornstarch.

Trump Jr. lashed out at the prankster who sent the envelope to his wife.

“Thankful that Vanessa & my children are safe and unharmed after the incredibly scary situation that occurred this morning. Truly disgusting that certain individuals choose to express their opposing views with such disturbing behavior.”