According to a McCain spokesperson, via The Trail, another similar threatening letter was sent to another McCain office in Manchester, New Hampshire, but no word on whether that letter contained any white powder as the one sent to his Denver campaign office did.
Four workers present in the office at the time the letter was open, drove themselves to a local hospital to undergo decontamination procedures as a precaution, although no symptoms or signs of exposure to a toxic substance was present.
Initial reports had said there were anywhere from 5 to 25 workers in the office.
The white powder is contained in the letter is in the process of being tested and the results should be available later tonight.
John McCain was not in Colorado at the time, he was in Arizona.
CBS' The Horserace reports McCain spokesman, Jeff Sadosky, told CBS News' Michelle Levi, they "immediately notified local and federal law enforcement agencies and are looking to cooperate with them."
The Australian reports that Secret Service spokesman Eric Zahren says that the letter contained a "generic warning regarding the contents" and hazardous material experts, Secret Service and FBI joint terrorism task force agents were immediately called to the scene to quarantine the workers and evacuate the building.
This is the second incident in Denver in the last two weeks regarding potentially toxic agents, the first being the report here at Wake up America on August 13, 2008, where a Canadian man was found dead in a hotel in Denver and a container of what was believed to be cyanide was found in the room.
The two incidents are not related as far as anyone knows at this time, but with the Democratic National Convention being held in Denver next week, there has been heightened security in the area.
No reports available at this time as to where the letter received at the Colorado campaign office was mailed from or who it was addressed to.
Fox News is reporting that both the offices, the Colorado and the New Hampshire office, were evacuated and white powder was found in both letters.
AP is reporting also. CNN now as well.
Reported by Wake Up America