( CNN ) -- The nation 's oldest Army armor unit at Fort Carson in Colorado remained in lockdown for a second day Friday , after the post began investigating `` the unauthorized removal of government property , '' the military said . The lockdown applies to the 1st Battalion 66th Armor Regiment `` Iron Knights , '' an Army spokesman said . `` The 66th Armor Regiment is the oldest Armor unit in the United States Army , tracing it 's lineage to the beginning of the Tank Service in February 1918 , '' its Facebook page says . Fort Carson chief of media Dani Johnson declined to elaborate Friday on the type of property allegedly removed . `` This type of lockdown is a unit lockdown , which is at a commander 's discretion , '' Johnson said . Between 500 to 750 soldiers are affected `` at most '' at the 26,000-soldier installation near Colorado Springs , Johnson said . `` So you 're talking about a very small impact , '' Johnson said . This type of lockdown is not common , a spokesman said . The measure means that soldiers remain on-duty working on the base instead of being allowed to go home , CNN affiliate KKTV reported . The property purportedly missing was from that unit , and base authorities searched outgoing vehicles Thursday to make sure property was not being removed from the base , the affiliate reported .
` ` Iron Knights at Fort Carson remains in lockdown after property is missing . It 's `` the oldest the United States Army unit in Armor , '' since Thursday . Up to 750 soldiers at the 26,000-personnel post are locked down . This type of lockdown is not common , a spokesman says .