What a horrific situation! With so little information right now it's impossible to tell what happened at that house.
One thing that struck me though was the neighbor hearing two shots. IMO that seems like the murders were more "business" than personal, like an execution. I don't mean that literally as in a hit for hire but rather more like killing the parents being part of the crime but not the crime itself.
I'm having difficulty expressing what I mean... if it was personal then I'd expect more anger in the attack, like beating or stabbing the victims. It makes me wonder if the parents were killed simply to eliminate witnesses. If so then it very well may have been a home invasion. Or someone obsessed with Jayme getting rid of "obstacles." IOW, the parents may not have been the focus of the murders. JMO.
But if it was a home invasion then why do it when the house was occupied? Why not wait until it was empty to rob them? And why this particular house?
Of course none of this explains why Jayme is missing. If Jayme was the "goal" then she is indeed in danger.
If LE is able to decipher the 911 call it may shed some light on what transpired. In any case, no matter the circumstances I hope Jayme is found soon!