JOINT BASE MYER-HENDERSON HALL, Va. - A functional active shooter exercise took place on the Henderson Hall portion of Joint Base Myer-Henderson Hall July 17 to assess first responder reaction time and the reactions of a select group of JBM-HH staff and employees.

The breakdown of the exercise scenario was as follows: A military policeman portraying a shooter entered Building 12, home of Marine and Family Services, at approximately 9:45 a.m. The exercise shooter fatally shot a worker and roamed the building's hall and searched for open doors and additional subjects to shoot.

According to evaluators and law enforcement participants, there were two main objectives to take away from the emergency exercise - monitoring the response by JBM-HH emergency services and determining how building occupants reacted to the portrayal.

"We want as much realism as possible. We want to understand the good, bad and the ugly [of this exercise] and what can be changed," said military policeman and exercise participant Staff Sgt. Hunter Gough, who works out of the Headquarters Company, Headquarters and Service Battalion, Henderson Hall S-3 Training Office. "We're going to measure the emergency response and what people in Building 12 actually do."

According to Installations Operations Center Plans Chief Tom Yocklin, workers inside Bldg. 12 were intentionally kept off-guard in respect to the details of the exercise. Throughout the morning, times and circumstances of the event were altered to test readiness.

"We changed the scenario for an element of surprise," Yocklin said. "[The shooter] is going to go in there, shut the door and break the news that the exercise is starting right here, right now. The workers in 12 think he is coming in the front door, but we're planning that the shooter is going to start inside. We also have had them on a hold, stand-by status."

At 9:55 a.m., an active shooter radio notification was made, and at 9:58 a.m., four JBM-HH police department squad cars arrived at the intersection of South Gate and Northeast Roads to assist and aid the 30 employees inside Bldg. 12.

Following the evacuation of the Henderson Hall building, a number of the building's staff and employees summarized the reactions to the exercise.

"I had a plan in mind, but it went out the window," one worker said. "I hid; I didn't press [the panic] button initially. That was in the plan. I did press it after about 30 seconds."

The actual exercise was captured on video with a head-mounted portable camera and replayed at an after-action briefing held at the Joe Rosenthal Theater on Henderson Hall.

DES Third Watch Commander Lt. Troy Denison witnessed the exercise from inside Bldg. 12 and provided an account of the response: "We had a response force that initially responded and started setting up a traffic control point, so we could start directing traffic away from that immediate area," Denison said. "We shut the [Henderson Hall] main gate down and opened up the Annex Gate and the Hobson Gate."

According to Denison, a number of people inside Bldg. 12 escaped, but the majority of workers stayed sheltered in place.

"Overall, you did a very good job," Denison told Bldg. 12 workers who assembled at the briefing. "Once the people were able to secure ... and lock their doors, they did actually what I needed you to do."