That is correct! I did it on the bank! It's useful to have 2 exits lead to the same area so you can cover the area with just a single well placed smoke grenade. I'm sorry I failed to add that I used the AR, congratulations on completing hard! If you ever attempt this again, I highly recommend the AR since it can pop infecteds in only a few seconds and eliminate them (that is, make them float and no longer damage you) with only one dart of the 50 it spews in a single given second, by waving your cursor back and forth at a large cluster of infecteds it can eliminate them all with ease.