A retired NYPD detective who was part of an arson and explosions task force said Friday that while it is yet unclear what the intended target of Friday's explosion in Nashville was, he would not rule out the first responders and law enforcement.

Det. Bill Ryan told "America's News HQ" that it was unusual for the apparent bomber to leave an audial warning message of the impending blast.

"You have to really wonder what the motivation of the bombers are -- I don’t think this was one person, it was probably an organized group of people," he said. "I kind of think it was probably an idea to get first responders to come in -- [they] give them a 15-minute warning and all the first responders, the police and the firemen come in."

The warning call would start bringing all fire fighters and police officers to the area. Those first responders could have been the target they bombers were after, Ryan said.

At the same time, Ryan added it is also not clear whether the blast was a "trial run" for a larger attack, or a standalone explosion.

Returning to the possibility of an intended attack on police and firemen, Ryan said that in New York, there is still a "war" being waged by some segments of society against the NYPD.

"We had a police officer shot last night," he said, referring to Officer Connor Boalick, 27, who was responding to a domestic dispute in the Crown Heights neighborhood of Brooklyn on Christmas Eve. William Moss, 20, who is accused of the shooting, appeared in court on Friday, according to the New York Post.

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During his interview, Ryan also said that the Nashville suspect, who has not been unidentified, "didn't do themselves any favors by leaving themselves a lot of clues."

"The [audio]tape itself is a clue, the RV is a clue. Even though it’s blown up, much like the 1993 World Trade Center bombing in New York, the van was blown up but through putting the van back together again, but ... identifying the car, that was a big clue in locating the people," Ryan said. "A lot of this is going to be [done through the] ATF and its national response team as well as the local police, trying to put that car together again."