There will be (or is ongoing) a military tribunal. It will all be done by the code of law. That probably will result in death penalty for many of them.

Usually two methods, the convict may choose: hanging on a gallow or shot by a firing squad.

I do not suggest the let them die slowly or in a crucial way. Believe me, the only thing that dies is their bodies. But their spirits will suffer in a sphere, no one wants to go.