The threat was clear. Canton Police Officer Bobbie Cromer was shouting “I’m going to kill everyone!” as he unloaded a few rounds into the ceiling of a Tippens Elementary School classroom.

Moments later, three officers stormed into the room, guns out and fingers perched over the triggers. One lay motionless in the hallway after taking a stray bullet to the chest. A few more shots were fired, then silence overtook the empty school.

But this wasn’t the silence of death or tragedy. It was the silence of concentration. Chief Mark Mitchell and his two assisting officers were hunched over a smartphone, watching a video replay of what had just transpired. Cromer, a training officer at the Canton Police Department, peeled back his goggles and mask to give the group feedback.

The department spent the week training its officers in Advance Law Enforcement Rapid Response Training (ALERRT), which prepares first responders to “isolate, distract and neutralize an active shooter,” Officer Pacer Cordry said.

The 8-hour course happens annually for each of the department’s 48 officers. They run drills on clearing a room, stopping a shooter and identifying victims. Once they’ve perfected their skills under the supervision of Cromer and other training officers, participants gear up with helmets, bulletproof vests and airsoft guns to practice a series of real-time shooting scenarios.

“The training changes after every shooting,” Officer Pacer Cordry said. “We try to make scenarios reflective of recent events.”

This training has become increasingly common since the Columbine High School massacre in 1999, when law enforcement realized that waiting for SWAT or other tactics teams cost too many lives. But in the wake of last week’s attack on Pulse Nightclub in Orlando – the deadliest in modern American history – more than just the police want to be prepared.

The Marietta Police Department will be hosting a civilian training session on Monday night, from 6:30 to 8:00 at Marietta High School. Like the seminars held last December, Monday's session will go through ALERRT's "avoid, deny and defend" citizen survival strategies.

An identical session will be held by Canton Police at the Canton First United Methodist Church, also from 6:30 to 8:00 on Monday night.

In Jonesboro, the Clayton County Sheriff will be hosting three active shooter training classes at their office from 6:30 to 8:00 on July 9, 18 and 27.

“If the active shooter call ever goes out in our county,” Cromer paused to knock on wood. “There will be 150 cops on the way, I swear to you.”

RSVP to Marietta's training seminar at https://mpd-crase.eventbrite.com. Email Nikia.Browning@claytoncountyga.gov to RSVP for one of Clayton County's classes. Canton's session is first-come first-served, no RSVP required.