Investigators encountered "extremely unusual" facts surrounding the Nashville bombing, retired NYPD Detective Pat Brosnan said on Monday.

"This was a Christmas miracle in Nashville. The officers, I salute them; I know they do it every day, in and out. But, astonishing display of valor and courage," Brosnan told "America's Newsroom."

Brosnan said that though the motive is "unknown," the "series of known facts" regarding the explosion is "historically unprecedented."

"What you have here for a bomb maker is the intent to maximize property destruction and, almost unheard of to my knowledge, minimize the loss of lives. Extremely unusual."

ANTHONY QUINN WARNER: WHAT TO KNOW ABOUT THE NASHVILLE BOMBING SUSPECT

Federal authorities on Sunday identified the suspect in the Christmas Nashville RV bombing as Anthony Quinn Warner.

Investigators said they used DNA to identify human remains found at the scene to be that of 63-year-old Warner. The FBI said they also matched the RV’s vehicle identification number to a registration belonging to Warner.

Warner is believed to have acted alone, but authorities have yet to determine a motive. He was not known to law enforcement prior to the Christmas blast.

The explosion rocked Nashville early Christmas morning, well before downtown streets were bustling with activity. Before the blast, a recorded announcement warned anyone nearby that a bomb would soon detonate.

Sources say Warner was a computer consultant who worked as an independent contractor for Fridrich & Clark Realty, a Nashville-based real estate firm.

Fridrich and Clark’s president Steve Fridrich told Fox News that Warner was never an employee at the company but occasionally serviced its computers. Fridrich said Warner announced his retirement earlier this month and has had no further contact with the company since that time.

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Brosnan said the bombing is "frightening," reacting to an NYPD memo that warned cops could be a target of IED, vehicle attacks, etc.

"You can be certain that an army of highly skilled investigators are tearing apart Warner’s life. Completely ripping it to shreds and reconstructing it inch by inch and piece by piece to understand the most elusive of all since he is gone and we don’t have a known co-conspirator, what the motivation was. Extremely critical factor."

 Fox News' Bradford Betz contributed to this report