The FBI has begun an investigation into the toxic powder that was discovered in a package sent to Arizona Rep. Raul Grijalva.

Adam Sarvana, spokesman for the congressman, said that when staff was routinely checking the mail in the Tuscon office they discovered a white, powdery substance and two drawings of swastikas inside an envelope.

The Tuscon Fire Department was called and was able to confirm that the substance found was, in fact, toxic.

There were at least a dozen people in the office at the time of the incident and each of them were checked on the scene before they were sent home. The incident happened around 12:30 pm on Thursday.

Scientists at the FBI laboratory in Phoenix are running a full analysis of the substance.

Grijalva has had three security issues at his district offices this year.  In April he had to close two of his offices due to threats he received in regards to his position on immigration legislation.  Following that, in July a bullet shattered the window of his Yuma, AZ office.

Grijalva has expressed his concern for the staff that works for him and the people that visit his offices given the security issues.