What we know about the 2 officers credited with stopping Nashville shooter

received the first call of an active shooter at The Covenant School, where a mass shooting left three 9-year-old children and three adults dead. In 911 audio recordings released by Nashville authorities, voices could be heard pleading for help in hushed tones as sirens, crying and gunfire all sounded in the background.

"Please hurry," one caller pleaded to the 911 dispatcher.

Dozens of police officers descended on the private school, some taking fire as they arrived, and the shooter was killed within 14 minutes of the first report of the shooting — likely saving "many lives," according to Nashville Mayor John Cooper. 

Rex Engelbert and Michael Collazo, both members of the Metropolitan Nashville Police Department, fatally wounded the shooter, police said. The department on Tuesday released surveillance video of the officers' response. 

Engelbert and Collazo were not made available for interviews and the police department didn't release any further information. 

Here's what we know about them:

Officer Rex Engelbert

Body camera footage shows Engelbert, a four-year veteran of the MNPD, pulling up to The Covenant School and grabbing a rifle from the trunk of his police car.  He unlocks the school doors, saying, "Let's go, I need three," as he enters the school with three other officers. 

The police team canvases the downstairs rooms until Engelbert hears shots from above, "it sounds like it's coming from upstairs," he says and runs straight up the school stairwell.

Alarms whirring and booming rifle shots could be heard in the footage as the officers locate the shooter three minutes after entering the school. Engelbert fires his rifle at the shooter.

Those who know Engelbert weren't surprised by his actions. "He's a gentle giant," his brother told The Chicago Tribune.

A Chicago native, Englebert graduated from Loyola Academy, a Jesuit school, in 2014. In a statement, the school said it recognized the role that the "quick response" of Engelbert played in the school shooting and that it will "pray for him and all our first responders who are called to a life of service to others every day."

Officer Michael Collazo

Officer Michael Collazo is seen in the bodycamera footage running up the school's stairs with three other police officers. He shouts, "Shots fired!" and directs the team to "go right." He locates the shooter and pushes in front, with his handgun raised, and fires. "Suspect down, suspect down," he radios. 

His actions also did not surprise friends and family that know the nine-year MNPD veteran and Marine Corps veteran. His sister told Fox News that Nashville native Collazo is, "braver than she ever imagined." 

Collazo served six years in the Marine Corps until 2016, reaching the rank of sergeant, sources confirmed to CBS News. While serving, Collazo was awarded a Global War on Terrorism Service Medal, among other accolades. Collazo was last stationed in Smyrna, Tennessee.

Eleanor Watson contributed reporting

In:
• School Shooting
• Nashville
• The Covenant School