[hiedeemom]

But, by this standard, does it create negative Karma if I must take life to save the lives of others?

the intention here is to save the life of others. thus it does not predominantly create negative karma

although karma (action) comes from intention, the importance of intention is it effects the quality of the result, i.e., how the mind feels after the karma is performed

so life may be taken to save the lives of others. this may result in some trauma. but in the long term, when the action can be justified by one's conscience then dissolving any traumatic effects is easier