Raycast (Shooting) Going through objects!

Hey, This is my first game using unity, and I am trying to make a top down shooter, Now I have shooting working and the objects being destroyed when its health gets to 0, however my raycast is going through objects, meaning I can shoot through anything to destroy my enemy cubes! Any help on how to get the Raycast to stop on the first object will be greatly appreciated!

if (CanShoot()) { Ray ray = new Ray(spawn.position, spawn.forward); RaycastHit hit;

         float shotDistance = 20;
         if (Physics.Raycast(ray, out hit, shotDistance, collisionMask))
         {

             shotDistance = hit.distance;

             if (hit.collider.GetComponent<Entity>()) {
                 hit.collider.GetComponent<Entity>().TakeDamage(damage);
             
             }