So, in eleven minutes, Gotham City is going to blow up. A lot can happen in eleven minutes, in a movie, when a nuclear explosion is imminent.
First, we have Blake leading the orphans (and some other citizens) on an exodus out of the city. Depending on where they are in relationship to the bomb, they’ll all die in the explosion regardless of whether they get across the bridge or not, but let’s say that somehow crossing the bridge will magically get them out of harm’s way. Blake gets them halfway across the bridge and runs into another police force (Newark?), whose job it is to keep people from trying to escape (for the public good). As at the top of the sequence, it’s a confrontation between civilians and police, but the positions are reversed. No civilians were in the fight against Bane’s army, because they’re all here with Blake confronting another police force. (The police, don’t forget, are the “thin blue line” separating civilians from criminals — it’s their job to confront thugs, they’re urban warriors. It’s appropriate that the police don’t enlist civilian aide in their attack on Bane’s HQ, just as it seem garishly inappropriate for a police force to threaten to fire upon civilians whose only crime is to wish to escape a nuclear blast.)