Two McCain offices evacuated after letter threat

DENVER (Reuters) - Two offices of John McCain's U.S. presidential campaign, in Colorado and New Hampshire, were evacuated on Thursday, and several staffers were hospitalized, after a threatening letter arrived in the mail containing an unidentified white powder.

But within hours, the letter was traced by authorities to a Colorado jail inmate who has a history of sending threatening mail, and initial tests of the envelope and its contents turned up negative for hazardous materials, the U.S. Secret Service said.

The New Hampshire scare over a second envelope there was later deemed to be an unrelated incident brought about by anxiety over the threatening letter received in Colorado.

McCain, 71, a Republican senator from Arizona and his party's presumed nominee for president, was taking the day off from the campaign, spending the day at his home in Sedona, Arizona.

The first parcel, described as containing an unspecified threat and a powdery white substance, was opened by a staff member at the campaign's Centennial, Colorado, office, near Denver, at about 3 p.m. local time, Secret Service spokesman Malcolm Wiley said.

Four members of McCain's staff admitted themselves to a nearby hospital, and seven other staff members and four emergency personnel were quarantined as a precaution, Wiley said. He added that those in quarantine were likely to be released later in the evening.

None of the four individuals admitted to the Sky Ridge Medical Center near Denver showed any signs of illness, hospital spokesman Linda Watson told Reuters. Nor did any of the 11 quarantined, the Secret Service said.

Watson said the powdery substance was being examined by the Colorado Department of Public Health and results were expected later Thursday.

Jeff Sadosky, a campaign spokesman in suburban Washington, D.C., said both the Colorado office, which serves as the campaign's south central regional headquarters, and the Manchester, New Hampshire, office, were evacuated immediately.

He and Wiley said the envelope of concern in New Hampshire was initially deemed suspicious because it bore a Denver return address.

Wiley later said the Colorado envelope was determined to have been mailed by an inmate of a local county jail who has sent threatening letters in the past. The New Hampshire scare proved to be unrelated and brought about by anxious staffers.

The Democratic National Convention is due to open in Denver on Monday.

The postal scare comes weeks after a U.S. Army scientist committed suicide as federal prosecutors were preparing to indict him in connection with the 2001 anthrax mailings that killed five people in the aftermath of the September 11 attacks on Washington and New York.

(Reporting by Steve Gorman, Dan Whitcomb and Jill Serjeant; editing by Eric Beech)