As Rob [1] and I headed out to McDonalds for bathroom and food, we saw the plumber outside snaking out the sewer line from the building, a good sign.
Upon returning, the plumber was no longer around, and the neighbor said that the blockage has appeared to been cleared away (someone flushed a wad of paper towels down the toilet it seems). Now all that is left is to dry out the carpet and clean the shower stall.