Neighbors say Michael Guzzo never showed any signs of being a violent man.
But that changed quickly when he took a pump shotgun and murdered four of his neighbors and two of their dogs before killing himself.
Police think the entire incident happened because Guzzo was mad about the dogs barking.
Neighbors say Guzzo had complained and even left notes about the dogs barking but no one expected this.
"You think you know you're neighbors and then something like this happens" Nadia Weitzel told 12 News in Phoenix.
Cops in Phoenix admit there was "some indication that perhaps that was a problem."
Dead are 66 year old Bruce Moore along with his daughter, Renee and her husband Michael. Also killed was 17 year old Shannon Moore.
Cops say after the shootings Guzzo fired the shotgun toward another apartment and then went into his townhouse where he put the gun to his own chest.
Weitzel heard the shots and later figured realized the significance. “That last gunshot was the guy killing himself” she said softly.