It would be interesting to see the breakdown of victims known to the perpetrator, although I am not certain that information is necessarily available.
This data is somewhat dated now, but the breakdown here is interesting:
https://www.crimestats.aic.gov.au/NHMP/
Only 10% of victims were strangers to the perpetrator and only 13% of the overall number of homicides occurred by gunshot wound. I imagine the numbers might be slightly different in NOLA/the US.