Multi-attacking multiple mobs

Guys,

Couldn't find the answer to this one. Let's say I have a player with a very high skill (melee, ballistic or warp) and I have 3 mobs of 10 enemies rushing him. Can he really use a multi-attack action to target each of the 3 mobs (penalty +4 to the DN) and have a chance at killing multiple enemies from each of the mobs? Saw this during a let's play when a lucky roll pretty much decimated half of the map of enemies in one attack😃

Does one mob count as one enemy during the multi-attack action?