ABC News’ Ron Claiborne, Bret Hovell, Jason Ryan and Barbara Garcia Report: Sen. John McCain’s campaign offices across the U.S. are on high alert, following the evacuation of his Denver office after an unidentified white powder was found. A McCain office in Manchester, New Hampshire received a a similar letter, though it did not contain powder, U.S. Secret Service and McCain campaign officials tell ABC News.
A staffer in Denver opened an envelope that had been sent to the campaign which contained white powder and a threatening letter.
"As a precautionary measure we have closed the office and staff are being examined by medical personnel," said McCain campaign spokesman Tucker Bounds.
The campaign says there were between five and ten people in the office at the time, and that they were taken to a hospital to get checked out.
So far no details have been released about the threatening letter.
The Arapahoe County Sheriffâs office is working in conjunction with the Secret Service, the FBI and HAZMAT teams.
Denver is the site of the Democratic National Convention, which will open on Monday.