If one (or both) of the squads is a KEU manning a SW or a Gun, the firer can instead choose which target is hit prior to - and in place of - a Random Selection DR. C13.31:
...As a one-shot weapon, a PF may not directly affect more than one unit when fired at an Infantry/Cavalry target (see 8.31) unless the Random Selection DR indicates several units are affected. However, once a hit is gained vs a multi-target Location and prior to any Random Selection, the firer can select the unit to be affected, provided that unit is Known and manning a Gun/SW.