Five staff members and a police officer were being evaluated Thursday night after a suspicious white powder was discovered inside an envelope in the fifth-floor mailroom in New York’s Trump Tower. The envelope was mailed to Donald Trump’s campaign office and addressed to the Republican presidential frontrunner. The substance was determined to be non-hazardous, but officials are still testing it to find out what it is. It was unclear if the envelope also contained a letter, but a member of staff alerted police upon opening the mail. The incident comes a month after an envelope containing a non-hazardous white powder and threatening letter was sent to Donald Trump’s son Eric.