A letter containing an unidentified white powder sent to the home of Donald Trump Jr. in Jupiter, Florida, prompted emergency crews to respond on Monday.

Trump Jr., the eldest son of former President Donald Trump, was at his home in Jupiter, Florida, when he discovered the envelope containing a death threat and the substance, which investigators were working to identify on Monday night.

“The test results of the substance came up inconclusive on what it was exactly, but officials on the scene do not believe it is deadly,” a spokesman for Trump Jr. said.

This is the second time he has been the target of a letter containing white powder. In 2018, his then-wife, Vanessa Trump, was sent to the hospital on February 12 as a precaution after opening the letter containing powder, which law enforcement officials later determined was not harmful.

The man convicted in the 2018 case sent a similar white powder letter to the 2024 Republican primary frontrunner’s other adult son, Eric Trump, during the 2016 presidential campaign that also turned out to be non-hazardous, prosecutors said.

Police, fire, and hazmat units immediately responded to the residence in Jupiter’s Admiral’s Cove neighborhood. Some responders arrived wearing protective suits, boots, hoods, and gloves to investigate, the sources said.

U.S. postal officials are assisting in the investigation, the sources said. The Palm Beach County Sheriff’s Office also assisted federal law enforcement with the investigation.

The U.S. Secret Service declined to comment, but two federal law enforcement sources confirmed that Trump Jr. is no longer a Secret Service protectee.

“The FBI, along with our local law enforcement partners, responded to an incident involving a suspicious letter sent to an address in Jupiter, Florida. We encourage the public to remain vigilant and report any suspicious activity to law enforcement,” the FBI Miami field office said.

Monday’s incident comes amid threats against political candidates and public officials.

A New Hampshire man was charged in December with sending threatening text messages to three presidential candidates, including Republicans Vivek Ramaswamy and Chris Christie, who have since dropped out of the race. 

Separately, former U.N. Ambassador Nikki Haley, the former president’s only prominent GOP opponent in the Republican presidential primaries, was targeted in two swatting incidents around New Year’s Day.