"You need to be on yellow alert in all your waking hours," he said. "You know, don't keep your head in the clouds; be aware of what's going on and listen to that internal radar. Listen to that inner voice. What people need to do is they need to observe, not just look. They need to listen, not just hear someone. These are the things that trained professionals do."
Stanton said there are three immediate steps to take if you're suddenly in the middle of a deadly shooting: "Identify what's going on, recognize the situation, and have an exit strategy."
To put these theories to the test, Benton, Dorney and the Bethlehem Police Department set up an experiment at Muhlenberg College in Allentown, Pa. ABC News sent out word that police were offering free gun training. And from those who were interested, six people with gun experience ranging from none to more than 100 hours at a range were chosen to take part.
After going through a basic safety course that covered more training than almost half the states in the country require to carry a concealed weapon, the participants were given a real glock handgun loaded with simunition bullets -- bullets that are filled with a kind of paint that does not injure someone on contact.
The participants then headed from the training class to a lecture on protective gear. In the lecture hall were cops or people working with ABC posing as other students taking part in the day's training. None of our participants knew that in moments they would be jolted into an intense and terrifyingly real simulation of an attack by a gunman.
What happens when the gunman bursts through the door? Will the students fall into the same problems the experts talked about, or will they snap to action and cut the gunman down? Watch Diane Sawyer's special tonight to find the startling results, and learn how to best survive this worst-case scenario.