Scenario A:
Slow zombies have completely overrun my city, army has mobilized and is attempting to kill everyone?
Radio anyone I can asking WTF? Then, move on to my highly hostile irregular war scenario sheet.
Scenario B: Contain an outbreak that has completely overtaken a city. Fast zombies, small pockets of resistance remaining, all resources available.
Establish a cordon around the area, check anyone leaving and enforce a 48 hour quarantine. Enforce perimeter with dug in M2's and infantry.
Rush CAS aircraft to the area, and use anti-personal weaponry against any hordes. I'd imagine that a AC130 could do an entertaining number on large groups, as could choppers. Maybe an A10 with cluster munitions. I'd stay away from 500 lb plus bombs and incendiaries, I want to keep as many alive as possible. The locations of the hordes, as well as any clear signs of survivors (big help signs) are noted down.
Part 2: Thunder runs
Zombies can't do a bloody thing compared against heavy armor. I'd form as many rescue platoons as possible, comprised of:
3 Abrams - Preferably TUSK version. 4th tank of the platoon is used for perimeter duty.
Acts as road plow and tow vehicle as needed. Provides heavy fire support and hamburgs zeds.
4 Bradley IFV - M2 version
6 infantry each, armed with a mix of shotguns, M4's, and at least one LMG per squad. The vehicle provides additional firepower with its Bushmaster cannon.
2 MRAPs - Possible be made in the area out of a delivery truck and liberal amounts of steel.
Effectively an armored truck, used to get survivors out of the conflict zone.
Cruise through the city, running over any zombie in their path. Facing no real opposition, they'd pull back relatively conservatively to refuel and rearm. The noise inherit with continual firing of cannon would attract a ton of zeds, to be cut down by the armor or aircraft.
Move to any accessible buildings that are marked as having survivors. If the building has a still suitable barricade, get the survivors to the MRAPs. Otherwise, the LT on the scene makes a judgment about clearing the building. If needed, additional troops would be prepared to long rope onto roofs.
Get all clear survivor areas evacuated, once that is done, start securing the city one building at a time. Move armor outside, storm building with infantry, rinse wash repeat. Most of the zeds are expect to have been lured outside and killed already. Start posting designated marksmen and snipers on rooftops to target and kill any undead they see.