SAN ANTONIO - A team of pretend gunmen stormed into a high school graduation at The Freeman Coliseum.
The scenario and drill included the gunmen opening fire on the crowd.
The fictitious scenario set the stage Thursday for the largest mass casualty exercise ever held in San Antonio.
The San Antonio Mass Casualty Exercise and Evaluation is an annual exercise designed to assess the capabilities of hospitals and emergency agencies.
Nearly 700 volunteers and role-players acted as victims, friends and family members.
"The more you sweat in training, the less you bleed in battle," Bexar County Sheriff Javier Salazar said of the drill. "We may all the sudden say, 'You can't use this exit, there's a gunman here, or, this fire hydrant isn't working.' We want to capture some of the real things that'll go wrong in real life."
The pretend scenario included rushing the injured victims to Brooke Army Medical Center, where medical staff was ready and waiting as a large number of the wounded arrived.
"Something of this scale certainly stresses the system so you can find those areas where you might have to sure those things up," said Col. Patrick Osborn, deputy commander of surgical services.
The make-believe victims were prioritized by injury. Those with life-threatening injuries were taken into the emergency department and treated first.
Osborn explained the many factors that go into BAMC being just one of two Level 1 trauma centers in South Texas.
"We provide a higher level or care with resources, expertise to be able to take care of any sort of traumatic injury that might be encountered in this area," he said.
The active shooter and mass casualty drill was put together in three months and those inside Freeman Coliseum and in the emergency department agreed the exercise kept them on their toes and ready for the unexpected.
"This is certainly a key to preparation for an event that may affect San Antonio or southern Texas. It allows us to insure that we have the resources and the skills available to respond to something like this," Osborn said.
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