Units engaged in hand-to-hand fighting are far too busy to use missile weapons and therefore may not shoot.
Players might wish to shoot at targets that are engaged in hand-to-hand combat. This is possible but not necessarily a good idea as your troops are likely to hit the wrong target and kill a friend rather than an enemy. Troops fighting hand-to-hand are taking part in a vast swirling melee, and under the circumstances it is virtually impossible for distant shooters to tell friend from foe or get a clear view of the target.
Troops are permitted to shoot at units in hand-to-hand combat but if they do so hits must be divided equally between both sides. Odd hits are allotted to either side randomly such as by rolling a D6: a score of 1-3 = a hit on your side, while 4-6 = a hit on your enemy. On the whole, it is not a good idea to shoot into hand-to-hand combat.