How to make multiple range damage

Hello everyone, i make a tower defense and right now i want to make a tower that will shoot in multiple targets in the same time. Like it was in warcraft 3 tower defense maps. For example my tower has 4 arrows flying from it in the same time in the different enemies. And when before this tower is only single enemy, it shoots only by one arrow in this single target. When for example 4 enemies are coming before the tower, it shoots in each one at the same time, by the different arrows. Please, help me. And the amount of enemy which are shot at the same time should be controlled for example in the script, and in the unity editor as well.