Their job is to prepare current and future first responders for the unthinkable.
Yet even the experts at College of DuPage's Homeland Security Training Institute say they were as shocked as the rest of us by the Boston Marathon bombing.
"I was really surprised that a sporting event such as that would be the target of any terrorist attack, whether it's domestic or foreign." said Michael Casey, who is retiring from the Bureau of Alcohol, Tobacco, Firearms and Explosives to become manager of the institute's Suburban Law Enforcement Academy.
Casey said the tragedy in Boston reinforced his belief that everyone, including civilians, must be prepared and work together to keep all of us safe.
"You can't let fear dictate your life," Casey said. "Because if you do, then they (the terrorists) have won. But you must be vigilant."
Deanna Davisson says that's especially true here in the suburbs, where large groups of people gather at shopping malls, theme parks, schools, festivals and sporting events.
"The enemies we're facing are going to target soft targets," said Davisson, an assistant professor of criminal justice who teaches courses associated with COD's Homeland Security Certificate program.
"They're going to go to places where there is not a large police presence," Davisson added. "They're going to find the large groups of civilians who maybe aren't paying attention and target there."
So anyone who thinks suburban residents don't need to worry about the threat of terrorism is mistaken, according to Tom Brady, associate dean and director of the Homeland Security Training Institute.
"An event like the tragedy in Boston could happen anywhere," Brady said. "It makes no difference where you live, whether it's a big city or a small suburb."
Brady said residents need to be aware of their surroundings.
"If there's something out of place, they need to make sure they report it," he said.
Organizers of annual festivals say they already use a variety of security measures, including having police and private security officers. Some events have security personnel inspect bags at entrances. Others use bomb-sniffing dogs to check the event location for explosives.
Still, it's almost impossible to completely lock down certain areas, including parks and marathon routes.
But if people join together and use their cellphones to report anything out of the ordinary, the odds of a terrorist act happening are minimized, according to Brady.
"The public has to understand that when they're going to any type of event, they always have to be on guard," Brady said. "They need to be the eyes and ears for law enforcement."
Davisson said the message to the American people should be that they're the front lines.
"So get yourself prepared for the fact we're living in a different world, at least for now," she said.
And if something tragic does happen, it helps when residents are able to offer assistance by knowing how to do CPR and other lifesaving tasks.
"If you go back and scroll through the photos of the incident in Boston," she said, "in most of them you're going to find John Q. Citizen rushing to the aid of someone else."
Joining a Community Emergency Response Team or a similar program is one way local residents can receive training to help their family members and neighbors in emergencies.
"Know what you're doing," Davisson said. "You don't want to be getting in over your head. But we've got an army of people out there who are ready and willing. They just need to be given the opportunity to connect with those kinds of programs."