An envelope containing an unknown white powder was sent to Donald Trump Jr’s mansion in Florida Monday, prompting a massive response from first responders, a spokesperson told The Post.

Authorities in hazmat suits and several fire trucks were seen at Trump Jr’s house in Jupiter, FL. after he received and opened a letter with the unidentified white powder inside, according to a source on the scene.

“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 spokesperson for Trump Jr. told The Post.

The incident was first reported by the Daily Beast.

Trump Jr. and fiancée Kimberly Guilfoyle purchased a $9.7 million mansion in Jupiter in 2021 after the pair departed from New York.

Jupiter police referred The Post to the Palm Beach County Sheriff’s Office, which handled the incident.

A message left for the sheriff’s department was not immediately returned Monday evening.