But someone made an interesting point that perhaps he thought she was threatening to kill herself and had wandered off when he made the call , he obviously did not think she was capable of her threat or of murder - or he himself would not have left guns around . then he heard a shot and dropped the phone
If she shot everyone else and wandered away leaving him alive then he would either:
1) get the hell out of there to save his ass
2) call police demanding an ambulance be sent and then either get out to save his own ass or go try to help save her if he felt she was going to kill herself.
Calling Jeremy to Keep it in the family would not be an option if she already shot people.