Democrat nominee Hillary Clinton's campaign headquarters were evacuated on Friday (21 October) evening after an envelope containing a suspicious white powdery substance was found in the office. The New York Police Department (NYPD) is reportedly investigating the case.

The envelope was first delivered to Clinton's midtown Manhattan office at around 5pm local time (10pm BST). Two of her interns opened it and found a suspicious white substance inside. They then took it to the campaign headquarters in Brooklyn, New York Post quoted some police sources as saying.

Lt. Thomas Antonetti of the NYPD confirmed to CNN that the envelope was first sent to the Manhattan office on 45th Street, where all of her mails are sent, and then taken to the Brooklyn headquarters at around 5.30pm. He added that they were investigating if the substance is toxic.

Four people, who opened the envelope, were reportedly exposed to the substance but there were no reports of injuries, the NYPD told DailyMail.com.

The incident took place when Clinton was in Ohio taking part in an election rally. This is reportedly the first occasion when a suspicious substance was sent to her office. Her rival, Republican nominee Donald Trump and his family were reported to have received such suspicious substances several times in 2015, but all those substances were found to be non-toxic.