Figuring out OOP in AS3 - actionscript-3

Question

I am new to AS3 and OOP concepts. I have one class called AlienShips
I have a laser beam and I am trying to check collision of beam with all the alienships on my stage. But collision gives weird results.. it detects all the alienships and not just one specific ship. So when my beam hits one of the alienships it destroys all the rest of the ships as well.
Here is the code of my AlienShip
public class AlienShip extends MovieClip {
private var laserBeam:CannonBeam;
public function AlienShip(){
trace("create new alien ship");
addEventListener(Event.ADDED_TO_STAGE, enterFrameHandler );
}
private function enterFrameHandler(event : Event) : void {
removeEventListener(Event.ADDED_TO_STAGE, enterFrameHandler);
}
public function destroySelf():void{
parent.removeChild(this);
removeEventListener(Event.ENTER_FRAME, enemyLoop);
}
public function hasCollided(otherObject:MovieClip):Boolean{
return this.hitTestObject(otherObject);
}
}
Here is my main document class on stage where I instantiate all my base class alien objects as follow
public class RaidersMain extends MovieClip {
private var alienOne:AlienShip;
private var alienTwo:AlienShip;
private var alienThree:AlienShip;
private var alienFour:AlienShip;
private var alienShipArray:Array = new Array();
public function RaidersMain(){
initGameElements();
}
public function initGameElements():void{
alienOne = new AlienShip();
stage.addChild(alienOne);
alienTwo = new AlienShip();
stage.addChild(alienTwo);
alienThree = new AlienShip();
stage.addChild(alienThree);
alienFour = new AlienShip();
stage.addChild(alienFour);
alienShipArray.push(alienOne);
alienShipArray.push(alienTwo);
alienShipArray.push(alienThree);
alienShipArray.push(alienFour);
cann = new CannonBeam();
stage.addChild(cann);
stage.addEventListener(Event.ENTER_FRAME, loop);
}
private function loop(event : Event) : void {
checkForBeamAlienCollision();
}
private function checkForBeamAlienCollision() : void {
for(var i = 0; i < alienShipArray.length; i++){
var currentShip:AlienShip = alienShipArray[i];
if(currentShip.hasCollided(cann)){
currentShip.destroySelf();
alienShipArray.splice(i,1);
}
}
}
But in the for loop it destroys all the aliens and not just the specific ship that the beam collides with in the for loop. What am I doing wrong? How do I correct the design of the aliens structure?