A radio crackled with chatter as first responders talked through an active shooter drill at the Evie Dennis Campus in Green Valley Ranch. Michael Eaton, chief of the department of safety with Denver Public Schools, listened as sirens wailed in the background.

“In a crisis is not the time to identify how well your plan works,” he said. Shootings “happen in a matter of minutes.”

Denver Public Schools participated in the two-hour drill on June 20, along with school safety officials from Jefferson County, Aurora, Adams 12 and Boulder Valley. A handful of students and educators from DPS participated as actors inside the building, while one person acted as a shooter.

The drill will help organizations find the strategy’s strengths and weaknesses in responding to a shooter, Eaton said. With so many entities involved, one of the most important aspects is how they all communicate with each other.

People who are the most effective in crisis situations are the ones who stay calm, he added. Drills help train safety officers to keep a level head.

DPS has invested $20 million in school safety, Eaton said. The department of safety has 135 staff members, including campus safety officers and emergency preparedness professionals.

Schools are fitted with video cameras, so the dispatch center is able to watch lockdown events in real time. During the drill, officials were able to communicate over the radio the location of the shooter in the building, as well as locations of any potential victims.

DPS has been working with Colorado-based I Love U Guys Foundation, which offers training programs in standard response protocols, Eaton said.

Each school in the district also goes through emergency training. DPS is included in the Denver Police Department (DPD) radio system, Eaton said. This way, if an event in the city could impact a school’s safety, the school can immediately go into lockdown procedures.

“We want schools to have very clear and consistent protocols,” he said.

Randall Wells, special operations chief with the Denver Fire Department (DFD), said they frequently work with DPD and Denver Health to run similar drills for random acts of violence. The response will often incorporate other resources such as RTD as a means of transporting people away from a dangerous area.

DFD is responsible for setting up incident commands during the drills, Wells said. The exercises go through the response to an active shooter situation, as well as evacuation and medical care afterward. He added that first responders also help set up communications for concerned families and children to reconnect with their parents.

With more shootings occurring, Wells said it is important to practice drills with schools so that children can be protected. Running the drills, he added, shows students that people are working hard to keep them safe.

The drills are a recognition that schools have “been a target for random acts of violence,” Wells said. “It’s a very hard pill to swallow.”