Travis Air Force Base in California said a false alarm led to a lockdown on the base Wednesday.
According to a Facebook post from the base, there were reports of gunfire on the base late Wednesday morning. The release says the base "immediately responded to ensure the safety of all its personnel, dependents and retirees."
The reports were later determined to be unfounded.
The false alarm came amid a two-day exercise by the 60th Air Mobility Wing to "train their ability to respond to emergency incidents."
Earlier on Tuesday, CBS San Francisco reported that the base went on lockdown due to an active shooter situation.
Travis Air Force Base is located in Fairfield, California, between San Francisco and Sacramento.