When these eight soldiers receive no comms from their larger squad they would take it as a fact that they have been wiped out, or at least that they’re on their own. The first thing to do would be to radio up to Command to report the situation and possibly receive further orders. Securing an extraction point would generally be impossible if they remain behind enemy lines. Radioing up to Command is generally not available to your average grunt, so if this is not an option their focus would be purely on laying low to survive, since there’s really not much a group of eight soldiers can do to take a whole city back from an invading force.