WASHINGTON, DC (WUSA9) -- Five months since the Navy Yard shooting, shots rang out at another DC military installation. Luckily it was just a drill at Joint Base Anacostia Bolling.
The hope is to save lives should the worst happen again.
Some of the Naval District Washington police officers responded last fall while Aaron Alexis was killing people at the Navy Yard and it's still a raw wound for some people here.
Lightly-armed two man teams race into the public health building at Joint Base Anacostia Bolling, where someone is firing blanks, and volunteers are lying on the ground covered in fake blood.
"It's important that we're prepared for this kind of situation," says Navy Capt. Anthony Calandra, the base commander. "We have to continue to do this."
These guys have good reason to drill. Besides the Navy Yard, there is the fact that these kinds of situations, active shooters, have doubled in recent years. A Texas State University study suggests people set out to kill a mass of people about once every other month in the US before 2008. But criminal justice professor J. Pete Blair says there is now an attack about once every month.
"There are a lot of things that keep me up nights," says Calandra. "And this is one of them."
Much like at the Navy Yard, some of the 'victims' here thought their attacker might have an accomplice. But it turns out there was not.
The base commander says police officers drill like this every year. That the exercise is not a response to the Navy Yard shooting. But it is designed to test officers. And to train them to save lives should a killer prowl the halls again.