Police normally train for this exercise inside a school or at the Red River Technology Center, where they also did some training today.
They try to go into buildings that are often targeted by shooters. That presents emergency responders with multiple challenges when it come to rescue and the capture of the gunman inside. Lawton Police Captain Alvin Winham explain how this could be an officer's worst nightmare.
"Someone that has actually gone in and is actually shooting randomly, they have no intent but to shoot people randomly whether they are going to flee or not they are just continuously, continuously shooting, " said Winham.
All departments big or small should be prepared for the event of tragedy.
"Through the history if you look at those, the size of the city does not matter, all the way from small towns to major cities, so no one is left out, everyone can be a victim to this,"said Winham.
Training or not, nothing can prepare first responders for what could lie ahead. Winham says that's why in Wednesday's exercise no one was told what to expect.
"We don't have where there's a standard, this is exactly how you have to do it, we have to set it up to where they have to think on the fly, so when they come in we run different scenarios to where they have to change it up, there won't be someone to tell them you need to turn this way or that, they need to be able to make those adjustments. "
Volunteers helped add to the chaos, something Winham says puts officers in a realistic environment.
"If they hear shots fired they're not going to know how to react to it, sometimes it's hard to distinguish where the rounds come from they don't know where they are going, and when they exit as we come in we have to try and figure out how to get through a crowd and identify suspects in that crowd and who are victims are. "
He also says emergency responders have to have a sense of urgency even when things appear calm.
"If you look at the videos of the Aurora shooting you'll see people kind of standing around, not running chaotically, some are in shock. They are in shock and walking not able to comprehend what's going on. It's something they've only seen on TV and not thought it would happen to them. We've got to work our way through that, people not listening to our commands, stressed, cause they don't know."
For the first time the Lawton Fire Department was included in the training exercise. Winham says firefighters are key to victim recovery and triage. He says officers will go in in front and behind them as they access who needs care first.