"I think the most difficult thing is to get through the mass chaos ... and to push yourself to keep going forward to stop threats, to minimize the amount of damage that someone is going to do," said Robert O'Donoghue, an officer in New Jersey.
But training helps officers know what to do, and that's exactly what happened Wednesday night in Indiana when police arrived on the scene, according to authorities.
"There's no doubt in my mind after watching the video that [they had] been well-trained, no doubt whatsoever," Smith said. "Those officers were professional. ... From the time they entered the store and the shooter is subdued is probably one minute or so."
Since the ALERRT program was first developed in 1999, more than 60,000 officers have been trained by it. Other nationwide programs offer similar training. The Justice Department's Bureau of Justice Assistance has given the program a funding boost to expedite training of state and local law enforcement officials.