Military base on lockdown after 'active shooter' drill gone wrong

A US military base was forced into lockdown mode after an 'active shooter' exercise got a little too realistic.

Joint Base Andrews, located near Washington D.C. in Maryland, raised an alert through their Twitter account, directing all personnel to take shelter after a gunman was reported on site.

“JBA is currently on lockdown due to a report of an active shooter. All personnel are directed to shelter in place,” the base wrote.

“"The incident is ongoing at the Malcolm Grow Medical Facility. First responders are on-scene now. All personnel continue to shelter in place,” an update read several minutes later.

The lockdown began just after 9am local time on Thursday with a US Defense official confirming the incident, Reuters reported.

The base had planned to hold an 'active shooter exercise' on Thursday morning, leaving many confused as to whether the situation was a drill or a real-life event.

Air Force One departing the base. Photo: AP

Joint Base Andrews confirmed police attended on the scene and secured the location.

Last month the base was locked down due to a bomb threat on the base.

“A woman walked into the Visitor Control Center on Joint Base Andrews and claimed to have a bomb strapped to her chest,” the base wrote on their Facebook page on May 13.

The situation was diffused after the woman and the area was searched and no explosive devices were found.

The base is the home of the Air Force One, the aircrafts used by the President.