A hazmat team and fire trucks were sent to the home of Donald Trump Jr. Monday afternoon after he opened mail and discovered white powder inside an envelope, a source told Axios.

The big picture: Trump, the eldest son of former President 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.
• Trump Jr. shared a copy of the letter with the Daily Caller, which published a photo of it. The Daily Beast first reported on the incident.

Zoom out: This is the second time Trump Jr. 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 nonhazardous, prosecutors said.
• Representatives for the Jupiter Police Department did not immediately respond to Axios' request for comment.

Editor's note: This is a breaking news story and will be updated with more information.