A scare at the campaign offices of John McCain in Colorado and New Hampshire.

His headquarters in suburban Denver was evacuated after a worker opened a threatening letter and discovered white powder inside.

Staff members in Colorado are now being checked out by medical personnel.

The campaign immediately notified local law and federal enforcement, and the offices, where dozens of people work, were evacuated.

Hazardous materials team was trying to determine if the powder found is harmful.

Several people in Colorado drove themselves to Sky Ridge Medical Center, but none showed any symptoms of exposure to a toxic substance.

McCain is taking the day off from the campaign, spending the day at his home in Sedona, Arizona.

The Democratic National Convention is set to convene in Denver on Monday.

Authorities don't know if there is a connection.

Authorities here in Colorado say the contents of the letter are quite alarming to staffers in McCain's campaign office