US Air Base Locked Down Due To A Mistake

A key US air base was put on lockdown after a member of a security forces team supposed to be carrying out a drill was mistaken for an "active shooter".

Joint Base Andrews in Maryland - which is home to the Presidential plane Air Force One - was put on alert and released several tweets telling staff to take shelter.

During the lockdown, Homeland Security Secretary Jeh Johnson said during a news conference there was an "unfolding situation" at the base.

But, sometime after posting a partial "All clear", it revealed the lockdown had been caused by confusion during an exercise practising for an attack.

The base tweeted: "The incident that occurred this morning has been cleared as of 10.40am. First responders determined there was no threat to the base.

"JJBA (Joint Base Andrews) was scheduled to conduct a no-notice active shooter exercise in the late morning on the opposite side of the base.

"However, reports of a real-world active shooter situation at the medical facility were miscommunicated before the exercise was able to begin.

"There was a misidentification of the security forces emergency services team who were conducting a routine inspection of the facility.

"'Fortunately, this was not a life-threatening situation,' said Col. Brad Hoagland, 11th Wing and Joint Base Andrews commander."

The Twitter feed said Colonel Hoagland added: "We take all threats seriously and reacted to ensure the security of those on the base.

"I applaud the quick reaction of our first responders in keeping the safety of our JBA family a number one priority. In addition, we thank our local authorities for quickly standing by and offering their assistance."

Tweets sent by the base initially instructed all personnel at the base in the Washington DC suburbs to find shelter and stay in place.

Even after the full lockdown was lifted, the base's Facebook page said for a period that the incident was ongoing at the Malcolm Grow Medical Facility.

Rodney Smith, a patient advocate who was in an unaffected building in the base's medical facility, told AP: "First it was an active-shooter exercise. Then it came back 'real world'."

Joint Base Andrews is where the US President's Boeing 747 is based and is about 20 miles (32km) from the centre of Washington DC.

After the all clear was declared, the base changed its Facebook cover photo to a picture with the attached headline "Always Vigilent".