It started with a radio call.
"There's a report of suspected gunshots fired, Wessman Arena, please respond."
Three minutes later, teams of four - two firefighters flanked by officers with guns drawn - made their way through the building searching for victims.
"It takes trust," Superior Battalion Chief Howard Huber said. "We have to trust the police when they say this area is safe. And they need to trust us that we know how to operate in an environment like that so that we're safe."
As they found each victim - slumped in the bleachers, laying on the arena floor, staggering out of the lobby - the person was evaluated, immediate care was provided and they were brought to paramedics staged at one end of the arena floor.
The April 30 event was the third joint active shooter training for the departments. The first took place on the University of Wisconsin-Superior campus in 2015, the second at Wisconsin Indianhead Technical College in 2016.
"This is so important," Superior Police Officer Marc Letendre said. "We don't want to be caught flat-footed. This is an important part of what we do and community engagement and being mindful that this is a reality in 2019."
Each department brings a different skill set, operational language and culture to the task.
"For us in particular, we rely on the fire department to use the skills that they employ day to day," Letendre said. "Because they typically address problems in a team environment with a command structure, whereas police officers, generally speaking, are more autonomous."
The biggest challenge is always communication, Huber said. Creating a unified command structure, training together and getting to know one another on a first-name basis lays the groundwork for future cooperation.
"That kind of thing, as we learned at the Husky incident, makes all the difference," Huber said, referring to the 2018 Husky Energy refinery fire.
Along with paramedics from Mayo Clinic Ambulance, police and firefighters ran the training scenario twice Tuesday. On the second run, they shaved 10 minutes off their time.
"Having repeated exposure to this type of training is what encodes muscle memory and it makes it much less likely that we hesitate, or that we don't deploy in the most efficient and effective manner," Letendre said.
Five volunteers became victims for the afternoon, complete with simulated gunshot wounds applied by firefighter Corey Larson. For EMT students Ja'lon Sventek and Dan Nerothin, it was a chance to get a first hand look at emergency personnel in action.
"They take it very seriously, and I like that," said Sventek, a member of the town of Superior Volunteer Fire Department.
Both agreed that the training was needed. Nerothin, of St. Cloud, Minnesota, said he was in the St. Cloud mall a few years ago when a mass stabbing took place.
"The mentality, 'It's not going to happen to us'" - you can't say that anymore,'" Sventek said. "It's been proven over and over again that school shootings can happen anywhere."