If these guys are foreigners as alleged, countless innocent people will be beheaded in attempts to get them out of prison. I don’t believe that they can allow them to come out of that mosque alive. We need a creative way to kill them without doing damage to the structure or violating international law.
What about aiming a large radar antenna at the building and microwave them?
We have a neutron pulse bomb that does just that. Fries the people, while preserving the structures.