Davis-Monthan Air Force Base was on lockdown Monday morning due to unconfirmed reports of gunshots. The Air Force Base is located near Tucson, Arizona.

After nearly being locked down for an hour, the base lifted the lockdown around 1:35 p.m. Eastern.

"Base personal (sic) are free to resume all normal operations. We will continue with updates as available," the base tweeted. 

Base officials told personnel to seek shelter during the lockdown.