Lehi • Organizers had been planning a mass casualty drill in Utah for months, but last week’s shooting in Las Vegas reminded participants that the possibility of such an attack is real.

Hundreds of high school students, first responders and law enforcement officers reported to Camp Williams on Tuesday morning to be the “victims” in the drill. They laughed and chatted with one another as red paint was applied to their faces and clothing. After receiving cards with information about their characters‘ medical conditions, they took their places as officers revealed the scenario.

In the drill, police staged a vehicle that had purportedly driven into a crowd of protesters. Once the vehicle stopped, the scenario continued with multiple active shooters who fled into trees.

Dispatchers reported shots fired as part of the drill, and officers from multiple agencies responded to the scene, heading to the trees where the suspects fled in staggered groups.

Sandy Fire Battalion Chief Tim Norris, chairman of the Salt Lake Valley Training Alliance, said the exercise is meant to help agencies learn how to better work with one another in crises and to identify better ways to respond.

He said he hopes the exercise gives the community a stronger “sense of awareness.”

To anyone caught in chaos like this, Norris recommended: “If you can — run, hide and then fight if you have to.”

Utah agencies began active shooter drills after the Columbine High School massacre in 1999, said Utah Highway Patrol Lt. Todd Royce.

In these exercises — and in real-life situations — the top priority for officers is to “neutralize the threat” by disarming or disabling the suspect or suspects, he said.

The “hardest thing” for law enforcement officers in such clashes, Royce said, is to pass by victims, some of whom are crying for help, in pursuit of suspects.

“They‘re not there to give assistance to the victims,” Royce said, because the longer a suspect is on the loose, the more victims accumulate.

Ariana Lopez, 16, and Aleya Stotesbery, 17, both students at Brighton, came to the drill with others in their criminal justice program.

“I see it as an eye-opener,” Lopez said of the drill. “Things do happen, and this training is necessary, just so you know how to approach this situation and what‘s the right protocol.”

They said the drill makes it easier to imagine responding to a mass casualty incident, and the hands-on exercise is valuable, “rather than just learning from a textbook.”

Medical first responders were at the scene, triaging the “victims” according to the extent of their injuries.

Two medical centers — St. Mark’s Hospital and University Hospital — also participated in the exercise, treating volunteers who posed as victims coming from the simulated attack and testing their capabilities under stressful circumstances.

At St. Mark’s, staff members took the simulation seriously, said Associate Administrator Sam Burgess.

“Even though we all know it‘s a drill, it’d be hard to tell,” he said.

Despite the sense of anxiety staff members feel when disasters occur and they don’t know how many patients will come in, Burgess said he was “amazed how everybody was calm but worked quickly.” There’s always room for improvement in communication and organization, he added, but he was proud of how his hospital responded.

Another hospital in St. Mark’s network, Sunrise Hospital and Medical Center in Las Vegas, took patients after last week’s attack, Burgess said, and the recent tragedy was “definitely in the front of our minds.”

“It reinforces to people that we need to be ready,” Burgess said.