INDIANAPOLIS - Consider the theater shooting in Aurora, Colo.; the Sandy Hook Elementary School shooting in Newtown, Conn.; the Boston Marathon bombing and Friday's shooting at the Los Angeles International Airport.
All were terrorist acts. All involved first responders.
National Guard Airmen and Soldiers are America's military first responders, and its members are sometimes called into action to support civilian authorities.
To be prepared, they train.
On Monday, the Indiana National Guard hosted explosive-detection training for local, state and national first responders. They included members with the FBI, Transportation Security Administration, Indiana State Police, Indianapolis Metropolitan Police Department and Marion County Sherriff's Department.
"One of the threats that is still out there now, in addition to al-Qaida, is home-grown terrorists. And their weapon of choice is this type of explosive, which is homemade," said John Beckius, an assistant federal security director with the Transportation Security Administration.
During training at the Indiana National Guard headquarters in Indianapolis, the FBI provided two types of homegrown explosives - triacetone triperoxide and hexamethylene triperoxide diamine.
These peroxide-based explosives are turning up more often, and are new threats post-9/11, said Tim Carpenter, FBI special agent and bomb technician.
While terrorists use these explosives more frequently, the first responders have to be ready to combat these new techniques. The first-response agencies rely on explosive-detecting dogs to find harmful substances.
"For most K-9 programs, it's the first time they've been exposed to these explosives," said Carpenter.
This is what the dog handlers called imprinting. Now that the dogs know the substances as explosives, they will be able to recognize them when working too.
"It's a worthwhile training scenario set up by the FBI and TSA," said Craig Patton, an Indianapolis Metropolitan Police Officer and K-9 training supervisor. "It's a chance to re-familiarize the dog with these particular odors. It's very beneficial."
Patton said the last time IMPD dogs encountered the peroxide-based explosives was in training prior to 2012 Super Bowl.
Other dog handlers agreed about the training's benefits.
For Sgt. Bill Carpenter, an officer with the Indianapolis Airport Police who works with a German shepherd named Aston, it's a chance for Carpenter's dog to hone his skills.
"It's good training," said Carpenter. "It's been six months since he's been exposed to the odor. He's good, but I need him to refine his techniques."
Carpenter wanted Aston to hunker down when he smelled the explosives.
Besides playing host to the first-response organizations, the Indiana National Guard has a part in the training, if only theoretical.
"If they find it, we’ve got to go get it," said 1st Sgt. Jason Wootten, as he watched the training. Wootten is the top enlisted Soldier for the 53rd Civil Support Team. The Airmen and Soldiers of the CST identify, assess, assist and advise the civil authorities - like the ones at this training - that request them to respond.
"We have a great working relationship with fire and police departments throughout our great state," Wootten said.
Beckius summed up why this multiagency training was so important.
"We are all supportive of each other," said Beckius. "When there are large events - Final Four, Super Bowl, the 500 --no department can handle them by itself."