It is not yet clear whether the substance was actually dangerous or not

The NYPD are investigating but say that no injuries have been reported

Clinton was not at the headquarters at the time but was on the campaign trail in Cleveland, Ohio - a swing state

Staff called the emergency services who evacuated the entire floor

They then took the letter with them to the Democrat's Brooklyn campaign headquarters at 5.30pm on

Hillary Clinton’s New York campaign headquarters was evacuated on Friday evening after staffers found a 'suspicious white powder' inside an envelope.

Two interns at discovered the substance when they opened the letter at the Democratic presidential candidate's Manhattan office at 5pm, the New York Post reports.

The staffers then took the letter to Clinton's campaign office in Brooklyn at around 5.30pm - exposing another two people.

Hillary Clinton’s New York campaign headquarters was evacuated on Friday evening after staffers found a 'suspicious substance' inside a letter

No injuries have been reported, the NYPD told DailyMail.com.

Emergency crews were called in and the entire 11th floor - where the campaign office is located - was evacuated on Friday evening.

The Secret Service and Office of Emergency Management were also on hand.

Police say it is not yet clear whether the 'white powedery substance' found within the envelope was dangerous.

A spokesman said the investigation is ongoing.

But there are fears the powder could be toxic after the infamous anthrax attacks in 2001 that followed September 11.

During that year, powdered anthrax was mailed to several news media offices and members of congress, killing five people and infecting 17 others.

Two campaign interns, opened a letter filled with a suspicious package and brought it to Hillary Clinton’s New York campaign headquarters in Downtown Brooklyn (pictured) triggering an evacution

Clinton was not in New York at the time of the evacuation.

The former first lady was at a community college in Cleveland, Ohio, as part of a multi-day campaign trail tour of the swing states.

This appears to be the first time that anyone has targeted Clinton or her campaign in this way.

But her Republican rival Donald Trump and his family have received several suspicious substances in the post in the past year - although all turned out to be non-toxic.

Emergency crews were called out to Trump Tower in August after the discovery of a suspicious substance in a subcellar of the Upper East Side building.

No-one was injured in the scare.

Hazmat teams and emergency crews surrounded Trump Tower in April after Trump received an envelope of suspicious white powder

In April, six people, including a police officer, had to be placed in isolation after an intern at Trump Tower in New York opened the envelope of suspicious white powder. The letter had been addressed to Donald Trump at Trump Tower, officials said.

The incident came barely a month after the billionaire's son Eric was sent a letter with suspicious white powder and a threatening message.

The handwritten note said: 'If your father does not drop out of the race, the next envelope won't be a fake.' It was signed 'X,' reported ABC News.

The last time anyone sent a suspicious package to the Clintons was a decade ago when a letter full of white powder was sent to f ormer President Bill Clinton’s Harlem office in 2006.