Several suspicious packages were discovered at the North American Aerospace Defense Command's (NORAD) Colorado headquarters, prompting the evacuation of the tactical command post.
The discovery led to the closure of Peterson Air Force Base, but possible injuries were reduced given that NORAD"S control room team was operating at a backup site in Cheyenne Mountain during the evacuation.
Personnel were at the alternate site because renovations are currently underway at their main building.
NORAD was formed as a joint U.S.-Canadian tactical command which is tasked with monitoring the airspace over North America. Cheyenne Mountain was NORAD's primary control room until the central command post moved to Peterson Air Force Base in 2006. The facilities in Cheyenne Mountain were developed in the 1960s and can reportedly withstand a nuclear detonation.
Because the organization's control team was locating at an alternate site, the evacuation did not interrupt any sensitive or security operations, Jeff Bohn, a spokesman at the Air Force base, said in a statement.
He added that some employees saw that packages and alerted security officials because the packages looked "out of place."
Tests were conducted on the packages which were found not to contain any biological, chemical, or radiological agents, but Bohn added that test were still being conducted and results could take several weeks to produce. The evacuation lasted nearly five hours.
NORAD official's decided to relocate the operational headquarters from Cheyenne Mountain, insisting that he change would save money and consolidate personnel.
NORAD shares its facilities with the U.S. Northern Command, which is tasked with defending U.S. territory from attack and helping civilian authorities.
There has been no word as of yet as to what specifically was suspicious about the packages that led to the evacuation at NORAD, and Bohn declined to give additional information at the time of the press conference when asked by reporters.