An unknown suspect sent Donald Trump Jr a letter containing a white powder substance on Monday, prompting multiple fire trucks and men in hazmat suits to respond to his Florida residence.

       According to The Daily Beast, three people familiar with the incident said Mr Trump, who is the eldest son of the former president, opened the letter and caused the white power to fly out of the envelope.

       A police department in Jupiter, Florida did not respond to the outlet’s request for comment.

       Mr Trump is not the only politician to have been sent white power. The substance is particularly nervewracking because it resembles anthrax, a weapon that can kill quickly if inhaled.

       Throughout the years, letters containing white powder have been used in hoaxes to terrify public servants.

       In 2011, a Colorado man admitted to sending letters filled with white power, later proved to be a sugar substance, to Former President Barack Obama, members of Congress and Argentine consulates.

       Last year, more than 120 Republican state lawmakers from Kansas, Tennessee and Montana were sent envelopes with a similar substance along with threatening notes. The Federal Bureau of Investigation has launched a probe into the incident.