ActionScript 3.0 :: Two Sprite Object Directing To Same Event

I have two sprite object and they direct to same event like follows:
sprite1.addEventListener(MouseEvent.CLICK, mouseEventHandler);
sprite2.addEventListener(MouseEvent.CLICK, mouseEventHandler);
private function mouseEventHandler(event:MouseEvent):void {
//how to do it here?
}
When click spirt1 or sprite2,it will call mouseEventHandler function,my question is how to determine which sprite is click in mouseEventHandler function,sprite1 or sprite?