Nashville vs. Uvalde shootings: A contrast in police responses

The swift and organized police response to the school shooting in Nashville, Tennessee, on Monday was roundly lauded by local officials and credited with preventing additional carnage and casualties.

A six-minute body camera video released Tuesday showed officers weaving through classrooms and corridors before approaching and neutralizing the shooter, who by then had shot and killed six people, including three students.

"They trained for that. And this moment happened and they didn't hesitate at all," Metro Nashville Chief of Police John Drake said Tuesday on "Good Morning America."

He added, "They responded, immediately went inside, knew the danger that was going on. Shots were being fired at the police cars. That did not deter them. They went anyway inside."

The law enforcement response in Nashville stood in stark contrast with the events that unfolded last year at Robb Elementary School, where officers waited 77 minutes before confronting and killing the shooter.

John Cohen, a former Homeland Security official, veteran police training expert and ABC News contributor, reviewed and scrutinized body camera footage available from both incidents and found that the officers in Nashville did "exactly what we hope those who put on the badge will do when they confront a dangerous situation like an active shooter."

"As a law enforcement professional, I watched The Covenant School video with an intense sense of pride," Cohen said. "I know how hard those officers' hearts are pumping and what that fear feels like. But this is why you sign up for the job. And they went in there and did it."

Cohen laid out several key points that demonstrated how the officers successfully responded. They communicated with school officials and immediately tried to assess the situation -- learning the number of suspects and determining where people were sheltered in place, he said. Moreover, officers operated with urgency and purpose to quickly clear rooms and communicate which rooms were cleared. After neutralizing the shooter, officers immediately formed security teams and began providing aid to the victims, he noted.

In Uvalde, responding law enforcement officials faced a deluge of scrutiny after a gunman shot and killed 21 people, including 19 students. After initially praising first responders for their efforts, state and local leaders eventually acknowledged cascading missteps that compounded the outcome of the attack.

"We failed," Col. Steve McCraw, director of the Texas Department of Public Safety, told ABC News. "And I say 'failed' and I said 'we' ... because collectively we did."