PETERSON AIR FORCE BASE, COLO. -- Peterson Air Force Base officials are continuing to investigate five suspicious packages that were found in a building Thursday morning.

Test results from the packages were negative of any chemical, biological or radiological agents, officials said. The packages were found to be office supplies.

As a precaution, personnel from select facilities were evacuated and a shelter in place directive was set at about 9:45 a.m. for the north side, base officials said.

A 500-foot safety zone was reduced to only the Eberhardt-Findley Building. That building is home to the North American Aerospace Defense Command and U.S. Northern Command. The all-clear was given at about 2:30 p.m.

Neighboring buildings were released from the increased security measures.

The 21^st Security Forces Military Working Dog section is also working the scene.

"We have highly trained emergency responders prepared for this type of response," said Col. Chris Crawford, 21st Space Wing commander. "We take our installation security very seriously and will continue to take all appropriate measures in our response."

The base’s north gate was closed for a short time but has since reopened.