WASHINGTON, Aug. 2 (Xinhua) -- Authorities gave all clear Thursday at a U.S. military base in the state of Ohio after determining a previous active shooter alarm was set off in confusion.

The Wright-Patterson Air Force Base was conducting an active shooter drill on one section of the base when "an unknown individual" called 911 to report on an active shooter incident the person believed to be real, the air base explained in a statement released on social media.

The call prompted authorities to carry out a security sweep of the base and ordered a lockdown, the statement said, adding that a firearm was discharged during the sweep to open a locked door.

Base commander Colonel Tom Sherman told the press after the sweep that there have been no real world active shooter.

The airbase is located near Dayton, Ohio. It hosts the 88th air base wing and has over 27,000 military, civilian and contract employees.