NORAD evacuated Evacuation Lifted at Headquarters in Colo.

NORAD headquarters in Colorado

NORAD headquarters in Colorado were evacuated for about 4 1/2 hours Thursday after employees found five suspicious packages, but the command's control room team was working at a backup location about eight miles away at the time and no essential missions were disrupted, officials said.

Employees became suspicious because something about the packages looked "out of place," said Jeff Bohn, a spokesman at Peterson Air Force Base in Colorado Springs, where the North American Aerospace Command is based.

Bohn declined to say what the packages looked like or what appeared to be amiss.

Tests performed on the packages ruled out chemical, biological and radiological agents, Bohn said. The packages were then removed and were undergoing other tests, he said.

Bohn said he did not know how the packages arrived or whether they had been screened before they were delivered. He said that would be part of the investigation.

NORAD is a joint U.S.-Canadian command that defends the skies over both nations and monitors sea approaches.