Israel kills Australian Aid Worker, page-181

From the international committee of the Red Cross

In which circumstances can medical establishments and units lose their protection granted by IHL?​

Specific protection of medical establishments and units (including hospitals) is the general rule under IHL. Therefore, specific protection to which hospitals are entitled shall not cease unless they are used by a party to the conflict to commit, outside their humanitarian functions, an "act harmful to the enemy". In case of doubt as to whether medical units of establishments are used to commit an "act harmful to the enemy", they should be presumed not to be so used.

The expression "act harmful to the enemy" is not defined under IHL. This body of law merely singles out a few acts expressly recognized as not being harmful to the enemy, such as the carrying or using of individual light weapon in self-defense or defense of wounded and sick; armed guarding of a medical facility; or the presence in a medical facility of sick or wounded combatants no longer taking part in hostilities.

Notwithstanding the lack of an agreed definition, the rationale for a loss of protection is clear. Medical establishments and units enjoy protection because of their function of providing care for the wounded and sick. When they are used to interfere directly or indirectly in military operations, and thereby cause harm to the enemy, the rationale for their specific protection is removed. This would be the case for example if a hospital is used as a base from which to launch an attack; as an observation post to transmit information of military value; as a weapons depot; as a center for liaison with fighting troops; or as a shelter for able-bodied combatants.
Exactly what Hamas has been doing.
Bad luck to terrorist organisations and those that support them.