"elite NG unit instead?"
The only "elite" NG unit I can think off are the full time chair warmers who get all the schools, awards and promotions, they think they're elite, but they would bleed to death from a paper cut.
A non-existent elite NG unit is more likey than the Delta Force in a situation like this. Honestly, I think they are probably SWAT or SWAT-like (like NYPD's ESU teams) from other cities and states.
MJ