Regarding all the suggestions to kill the creatures: don't forget that you'll have to clean up the carcasses, and any mess that they leave (blood, urine, feces) when you kill them. And squirrels may carry diseases, and insects (like fleas) that will spread those diseases.
If you deal with live traps, then you have to deal with emptying those traps.
If you can get them to leave, of their own volition, you save yourself some problems - but you should still clean up whatever mess they've already left in your home (get rid of their feces, replace or repair damaged electrical wires, clean their urine with bleach).
My suggestion is to use Arfin's recommendation of a one-way door, combined with sm's mention of food to attract the squirrels out, combined with fresh urine of an animal that the squirrels don't like (like snake, or fox, or something that's their natural predator). The urine trick may only work once - from what others have told me with similar problems, it scares them out, but they'll come back when the smell gets stale. A reapplication may work, but it's tough to know.
You'll also want to be sure that all entryways are completely sealed - you don't want the animals finding their way back in.
And, if I read correctly, you said you live in a townhouse (maybe that was someone else...). Is there a condo association? Do you own the outside of the building, or does the association? If it's the association's responsibility, let them know of the problem ASAP. You may be able to petition them for redress.