Shooting at the party, three suspects head back to one suspects home....2 leave that house, ready for action, one flees. Or stays at the house, and flees after the suspects shoot it out. Pipe bombs though.....not that many people are going to have pipe bombs laying around, a few select groups....
The fact there was a female shooter doesn't remotely rule out 'terrorism'/Paris style attacks, but it would be a first in the US, as far as I know.