Right? No. They were all killed.
Just more proof that owning a gun doesn't make you safer.
They haven't said who owned what guns, and given that they found several at the house, the gun used to kill all of them could have easily belonged to one of the adults that was killed.
Admittedly there are dangers to having guns in your house, but given random people coming into houses and using the residents' own guns to shoot them isn't super common, I'm not overly worried about it.
I think you're seriously overestimating how nicely the mugger is going to treat you. You think anyone would give you enough time to take out your phone, dial the number, tell the police you're being robbed AND where you are? I find that hard to imagine.