Well, the Ukrainians blew a bridge to the north road and the southern road is also fairly close to being cut off if it's not operationally cut of already.

Also here is an image of the same area from Google earth. I wanted to see if there were roads not marked on the map, there are some country roads though in some places they may just be paths through somebody's field(some are hard to see from this image, you have to zoom in). The ground looks fairly flat and open as well.
So it's hard to say if they can still get out or not, I think in small numbers with light equipment they still can for now, maybe, that's if it's not so flat and open that they can be seen from either side. But then it's also hard to say how many are still even in the city.