That is not known. It is known that the IDF shot at many of their civillians in Hamas captivity either with complete disregard for what they are shooting, or deliberately to avoid them being used as bargaining in hostage dealy.

The exact numbers however are unknown and before there can be an independent investigation, the extent will never be published. I wouldnt be suprised if the IDF and Israeli government have a good idea of the numbers, but they for sure will try to bury them.