Several fire trucks and hazmat-suited men were seen outside Donald Trump Jr.’s Jupiter, Florida, home Monday evening after the former president’s eldest son received a letter containing an unidentified white powder, three sources familiar with the incident told The Daily Beast. The white substance flew out of the letter when Trump Jr. opened it, one of the sources told the outlet. The Jupiter Police Department did not respond to the Daily Beast’s request for comment.  A representative for Trump Jr. said it is still unclear what the powder was, but confirmed that the former president’s son does not seem to be in danger. “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 told The Daily Beast.  Trump Jr. has been a vocal and unwavering supporter of his father, making campaign appearances with the senior Trump throughout the year. “It’s just become a little bit too commonplace that this sort of stuff happens,” Donald Trump Jr. told right-wing publication the Daily …